1st Grade Math Quiz: Add Within 100
20 questions · exam conditions
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Add Within 100Question 1 of 20

Add tens to tens: 34 + 20 =  

36
52
54
56
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1st Grade Math Quiz

1st Grade Math Quiz: Add Within 100

Practice Add Within 100 in 1st Grade Math with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Add Within 100, giving you a quick way to practice the rules, question types, and explanations that matter most for 1st Grade Math.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

Add tens to tens: 34 + 20 =  

  1. 36
  2. 52
  3. 54 (correct answer)
  4. 56
Explanation: When you add tens to a number, the trick is to keep the ones digit exactly the same and only change the tens. Here, the number 34 has a 3 in the tens place and a 4 in the ones place. Adding 20 means adding 2 more tens, so you go 3 tens + 2 tens = 5 tens. The ones digit stays 4. Put it together: 5 tens and 4 ones make 54. You can also count up by tens: 34 → 44 → 54. Two jumps of ten lands you on 54. The answer 36 is wrong because it adds only 2 (as if 34 + 2) instead of 2 tens — it treats the 20 like a 2. The answer 52 is a trap where the ones digit got changed by mistake; the 4 should never move when you add tens. The answer 56 comes from adding too much, like counting three tens (34 → 44 → 54 → 56 mixes up the jumps) or adding 22 instead of 20. Remember this: when you add a "tens" number that ends in zero, the ones digit of your answer must match the ones digit you started with. Since 34 ends in 4, your answer has to end in 4 — that alone points you straight to 54.

Question 2

Add ones to ones: 32 + 4 =  

  1. 28
  2. 34
  3. 36 (correct answer)
  4. 72
Explanation: When you add numbers, it helps to think about place value. Every two-digit number is made of tens and ones. In 32, the 3 stands for 3 tens (thirty) and the 2 stands for 2 ones. This question tells you to "add ones to ones," which means you keep the tens the same and just add the ones together. So look at the ones: 2 + 4 = 6. The tens stay as 3 tens, or thirty. Put them together: 30 + 6 = 36. That gives you 32 + 4 = 36. The answer 34 is what you get if you forget to add and just place the 4 where the ones already were, ignoring the 2 that was there. The answer 28 is a trap for subtracting instead of adding — 32 - 4 = 28 — so watch for the plus sign. The answer 72 comes from adding the 4 to the tens place by mistake, treating it like 4 tens (32 + 40 = 72); remember, a single-digit number is only ones, not tens. A helpful trick: line the numbers up by their place columns so ones sit under ones. Only the ones column changes when you add a one-digit number, so keep your eyes on those digits and leave the tens alone.

Question 3

The base-ten blocks show 43+543 + 5. What is the sum?

  1. 48 (correct answer)
  2. 47
  3. 43
  4. 45
Explanation: This question tests 1st grade addition within 100, specifically adding a two-digit number and a one-digit number using models (CCSS.1.NBT.C.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For 43 + 5, add the one-digit to the ones place (3 + 5 = 8), keeping the tens the same (4 tens), resulting in 48, without needing to compose a ten. The stimulus mentions base-ten blocks showing 43 + 5. Choice A is correct because adding 3 ones + 5 ones gives 8 ones, with 4 tens unchanged, making 48. Choice B (47) is a common error where students might subtract one or miscount the ones, often because they are still developing fluency in adding single digits. To help students: Use base-10 blocks extensively to visualize addition; connect visual models to written equations; practice many examples with and without composing; use number lines for counting on.

Question 4

Maya adds 28+528 + 5. What is the sum?

  1. 33 (correct answer)
  2. 32
  3. 23
  4. 285
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus one-digit (like 28 + 5), add the one-digit to the ones place (8 + 5 = 13), requiring composing a new ten (1 ten + 3 ones, so 2 tens becomes 3 tens, final answer 33). The stimulus describes Maya adding 28 + 5. Choice A is correct because 8 ones + 5 ones = 13 ones, which composes into 1 ten and 3 ones, so 2 tens + 1 ten = 3 tens with 3 ones = 33. Choice D is a common error where students write digits side-by-side instead of adding (285 instead of 33). This happens because regrouping/composing is complex. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 5

What is 45+545+5?

  1. Yes, the sum is 50. (correct answer)
  2. No, the sum is 49.
  3. Yes, the sum is 45.
  4. No, the sum is 55.
Explanation: 45 plus 5 equals 50. The sum of 49 is one less than the correct total. The sum of 45 repeats one of the starting numbers instead of adding them together. The sum of 55 is five more than the correct total. Only 50 correctly shows the sum of 45 and 5.

Question 6

Sofia has 43 stickers and gets 5 more. How many now?

  1. 47
  2. 48 (correct answer)
  3. 435
  4. 43
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus one-digit, like 43 + 5, add the one-digit number to the ones place (3 + 5 = 8), keeping the tens the same (4 tens). The stimulus is a story problem where Sofia has 43 stickers and gets 5 more. Choice B is correct because adding 3 ones + 5 ones gives 8 ones, with 4 tens unchanged, making 48. Choice C is a common error where students write digits side-by-side instead of adding (435 instead of 48); this happens because they treat numbers as separate digits rather than place values. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 7

Maya has 27 stickers and gets 5 more. How many altogether?

  1. 33
  2. 32 (correct answer)
  3. 27
  4. 25
Explanation: This question tests 1st grade addition within 100, specifically adding a two-digit number and a one-digit number, which may require composing a ten (CCSS.1.NBT.C.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For a two-digit plus one-digit number like 27 + 5, add the one-digit to the ones place (7 + 5 = 12), which requires composing a new ten (1 ten + 2 ones), so the tens increase by 1 (2 tens become 3 tens), resulting in 32. The stimulus is a story problem where Maya has 27 stickers and gets 5 more. Choice B is correct because 7 ones + 5 ones = 12 ones, composing 1 ten and 2 ones, so 2 tens + 1 ten = 3 tens with 2 ones = 32. Choice A (33) is a common error where students might add incorrectly by miscounting the ones or adding an extra unit, often because place value understanding is developing and they treat numbers as separate digits rather than composing when needed. To help students: Use base-10 blocks to show ones combining and exchanging 10 units for a ten-rod; practice with place value charts; teach 'when ones add to 10 or more, compose a new ten'; connect to real contexts like stickers.

Question 8

Use place value: What is 25+4025 + 40?​

  1. 65 (correct answer)
  2. 45
  3. 29
  4. 64
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus multiple of 10, like 25 + 40, add the tens (2 tens + 4 tens = 6 tens), keeping the ones the same (5 ones). The question asks to use place value for 25 + 40. Choice A is correct because adding 2 tens + 4 tens gives 6 tens, and the 5 ones stay the same, making 65. Choice B is a common error where students don't add, just use one number or add incorrectly; this happens because place value understanding is developing. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 9

Sofia has 43 stickers and gets 5 more. How many now?​

  1. 47
  2. 48 (correct answer)
  3. 435
  4. 43
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus one-digit, like 43 + 5, add the one-digit number to the ones place (3 + 5 = 8), keeping the tens the same (4 tens). The stimulus is a story problem where Sofia has 43 stickers and gets 5 more. Choice B is correct because adding 3 ones + 5 ones gives 8 ones, with 4 tens unchanged, making 48. Choice C is a common error where students write digits side-by-side instead of adding (435 instead of 48); this happens because they treat numbers as separate digits rather than place values. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 10

Do you need to compose a ten in 28+528 + 5?

  1. No, because 8+5=98 + 5 = 9.
  2. Yes, because 8+5=138 + 5 = 13. (correct answer)
  3. No, because you only add tens.
  4. Yes, because 28 is two digits.
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. Sometimes when adding ones, the sum is 10 or more, like in 28 + 5 where 8 + 5 = 13, requiring composing a new ten (1 ten + 3 ones, so 2 tens becomes 3 tens, final answer 33). The question asks if you need to compose a ten in 28 + 5. Choice B is correct because 8 + 5 = 13, which means composing a new ten is necessary. Choice A is a common error where students add incorrectly (8 + 5 = 9 instead of 13); this happens because students don't yet fluently recognize when to compose. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 11

Add tens to tens: What is 34+2034 + 20?​

  1. 36
  2. 54 (correct answer)
  3. 53
  4. 34
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus multiple of 10, like 34 + 20, add the tens (3 tens + 2 tens = 5 tens), keeping the ones the same (4 ones). The question asks to add tens to tens for 34 + 20. Choice B is correct because adding 3 tens + 2 tens gives 5 tens, and the 4 ones stay the same, making 54. Choice A is a common error where students add incorrectly or don't understand place value and add 20 to the ones instead of to the tens; this happens because place value understanding is developing. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 12

Add 61+761 + 7. What is the sum?

  1. 68 (correct answer)
  2. 67
  3. 71
  4. 61
Explanation: This question tests 1st grade addition within 100, specifically adding a two-digit number and a one-digit number using place value (CCSS.1.NBT.C.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For 61 + 7, add the one-digit to the ones place (1 + 7 = 8), keeping the tens the same (6 tens), resulting in 68, without composing. The stimulus is to add 61 + 7 by adding ones to ones. Choice A is correct because adding 1 one + 7 ones gives 8 ones, with 6 tens unchanged, making 68. Choice B (67) is a common error where students might subtract one or miscount the addition, often due to developing single-digit fluency. To help students: Practice with base-10 blocks for ones addition; use place value charts; connect to equations; emphasize examples without composing; relate to counting toys.

Question 13

Add tens to tens: 18 + 20 =  

  1. 28
  2. 36
  3. 38 (correct answer)
  4. 48
Explanation: When you add tens to a number, the trick is to keep the ones the same and only change the tens. Think of numbers as bundles of ten and leftover ones: 18 is 1 ten and 8 ones, and 20 is exactly 2 tens with no ones. To solve 18 + 20, add the tens together: 1 ten plus 2 tens makes 3 tens, or 30. Then bring down the 8 ones you started with. That gives 30 + 8 = 38. Notice the ones digit (8) never changed — only the tens grew. Now let's check the other choices. The answer 28 is what you'd get if you only added 10 instead of 20 — you added one ten too few. The answer 48 is the opposite mistake: you added 30 instead of 20, giving one ten too many. The answer 36 comes from a mix-up where the ones digit got changed to 6 — but adding a plain group of tens should never touch the ones place, so 8 should stay 8. A helpful strategy: when you add a "tens number" (like 20, 30, 40), circle the ones digit of the other number and promise to keep it exactly the same. Then just count up the tens. This keeps you from accidentally changing the wrong digit — the most common trap on these problems.

Question 14

Sofia has 27 stickers and gets 5 more. How many altogether?

  1. 32 (correct answer)
  2. 22
  3. 212
  4. 33
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus one-digit (like 27 + 5), add the one-digit number to the ones place (7 + 5 = 12), requiring composing a new ten (1 ten + 2 ones, so 2 tens becomes 3 tens, final answer 32). The stimulus is a story problem where Sofia has 27 stickers and gets 5 more. Choice A is correct because 7 ones + 5 ones = 12 ones, which composes into 1 ten and 2 ones, so 2 tens + 1 ten = 3 tens with 2 ones = 32. Choice C is a common error where students write digits side-by-side instead of adding (212 instead of 32). This happens because they treat numbers as separate digits rather than place values. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 15

Amir has 45 points and earns 5 more. How many points now?

  1. 49
  2. 55
  3. 50 (correct answer)
  4. 45
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus one-digit (like 45 + 5), add the one-digit to the ones place (5 + 5 = 10), requiring composing a new ten (1 ten + 0 ones, so 4 tens becomes 5 tens, final answer 50). The stimulus is a story problem where Amir has 45 points and earns 5 more. Choice C is correct because 5 ones + 5 ones = 10 ones, which composes into 1 ten and 0 ones, so 4 tens + 1 ten = 5 tens with 0 ones = 50. Choice A is a common error where students forget to compose a ten when ones sum to 10+ (like keeping it as 4 tens and 10 ones, but writing 49 or similar miscount). This happens because place value understanding is developing. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 16

Amir adds 67+3067 + 30. What is the sum?​​

  1. 90
  2. 97 (correct answer)
  3. 70
  4. 96
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus multiple of 10, like 67 + 30, add the tens (6 tens + 3 tens = 9 tens), keeping the ones the same (7 ones). The question states Amir adds 67 + 30. Choice B is correct because adding 6 tens + 3 tens gives 9 tens, and the 7 ones stay the same, making 97. Choice A is a common error where students forget to add the ones or add incorrectly; this happens because students don't yet fluently recognize when to compose. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 17

Chen adds 46+3046 + 30. What is his total?

  1. 79
  2. 76 (correct answer)
  3. 73
  4. 46
Explanation: This question tests 1st grade addition within 100, specifically adding a two-digit number and a multiple of 10 using place value (CCSS.1.NBT.C.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For 46+3046 + 30, add the tens (44 tens + 33 tens = 77 tens), while the ones stay the same (66 ones), resulting in 7676. The stimulus is Chen adding 46+3046 + 30 with a hint to add tens to tens and keep ones the same. Choice B is correct because adding 44 tens + 33 tens gives 77 tens, and the 66 ones stay the same, making 7676. Choice A (79) is a common error where students might add to the ones incorrectly or forget place value, often by treating the 30 as 3 and adding to ones, resulting in miscounts. To help students: Use base-10 blocks to show tens combining; organize with place value charts; teach 'add tens to tens, ones stay the same'; provide real contexts like counting pages in books.

Question 18

Add 34+2034 + 20

  1. 36
  2. 53
  3. 54 (correct answer)
  4. 34
Explanation: This question tests 1st grade addition within 100, specifically adding a two-digit number and a multiple of 10 using place value (CCSS.1.NBT.C.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For a two-digit plus a multiple of 10 like 34 + 20, add the tens (3 tens + 2 tens = 5 tens), while the ones stay the same (4 ones), resulting in 54. The stimulus is an equation 34 + 20 with a hint to add tens to tens and keep ones the same. Choice C is correct because adding 3 tens + 2 tens gives 5 tens, and the 4 ones stay the same, making 54. Choice B (53) is a common error where students might subtract or add incorrectly to the ones place instead of keeping it unchanged, often because they don't yet fluently recognize place value and add to the wrong column. To help students: Use base-10 blocks to show tens combining; demonstrate with place value charts; practice language 'add tens to tens, ones stay the same'; provide examples without composing; relate to real contexts like grouping toys.

Question 19

Add tens to tens: What is 34+2034 + 20?

  1. 36
  2. 54 (correct answer)
  3. 53
  4. 34
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus multiple of 10, like 34 + 20, add the tens (3 tens + 2 tens = 5 tens), keeping the ones the same (4 ones). The question asks to add tens to tens for 34 + 20. Choice B is correct because adding 3 tens + 2 tens gives 5 tens, and the 4 ones stay the same, making 54. Choice A is a common error where students add incorrectly or don't understand place value and add 20 to the ones instead of to the tens; this happens because place value understanding is developing. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).

Question 20

Use place value: What is 25+4025 + 40?

  1. 65 (correct answer)
  2. 45
  3. 29
  4. 64
Explanation: This question tests 1st grade addition within 100, specifically adding two-digit and one-digit numbers or two-digit and multiples of 10 (CCSS.1.NBT.4). When adding within 100, use place value strategies: add tens to tens and ones to ones. For two-digit plus multiple of 10, like 25 + 40, add the tens (2 tens + 4 tens = 6 tens), keeping the ones the same (5 ones). The question asks to use place value for 25 + 40. Choice A is correct because adding 2 tens + 4 tens gives 6 tens, and the 5 ones stay the same, making 65. Choice B is a common error where students don't add, just use one number or add incorrectly; this happens because place value understanding is developing. To help students: Use base-10 blocks extensively to show tens combining with tens, ones with ones; demonstrate regrouping with physical exchange (10 unit cubes for 1 ten-rod); use place value charts to organize thinking; practice language 'add tens to tens, ones to ones'; teach 'when ones add to 10 or more, compose a new ten'; connect visual models to written equations; provide many examples with and without composing; use number lines for counting on; relate to real contexts (stickers, toys, pages).