Understand Division as Missing Factor

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3rd Grade Math › Understand Division as Missing Factor

Questions 1 - 10
1

Find $72 \div 9$ by thinking: $9 \times \ ? = 72$.

7

8

9

81

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like 72÷9, you can think of it as a multiplication question: "What number times 9 equals 72?" or "9 times what number equals 72?" This is the same as solving the equation ?×9=72 or 9×?=72. If you know your multiplication facts, you can use them to divide: Since 8×9=72, then 72÷9=8. The missing factor (8) is the quotient. Fact families show this relationship: 8×9=72, 9×8=72, 72÷8=9, 72÷9=8 are all related. In this problem, we need to find 72÷9 by thinking 9×?=72. Using the missing factor approach: We know 9×8=72 from multiplication facts, so 72÷9=8. Choice C is correct because 8×9=72, so 8 is the missing factor that makes 72 when multiplied by 9, which means 72÷9=8. This demonstrates understanding that division finds the unknown factor in multiplication. Choice D is incorrect because it provides 81, which might come from 9×9=81 instead of using the correct fact; this error occurs when students make calculation errors or use wrong numbers. To help students understand division as missing factor: Explicitly teach the connection—"72÷9 means: what times 9 equals 72?" Practice fact families: if 7×6=42, then 42÷7=6 (division finds the other factor). Use arrays: "9 rows of how many equals 72 total? 9×?=72" Model thinking aloud: "I need to find 56÷7. I think: 7 times what equals 56? I know 7×8=56, so 56÷7=8." Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if 72÷9=8, check: does 8×9=72? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

2

An array has 32 dots in 8 rows; what is $32 \div 8$?

3

4

8

40

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like 32÷8, you can think of it as a multiplication question: "What number times 8 equals 32?" or "8 times what number equals 32?" This is the same as solving the equation ?×8=32 or 8×?=32. If you know your multiplication facts, you can use them to divide: Since 4×8=32, then 32÷8=4. The missing factor (4) is the quotient. Fact families show this relationship: 4×8=32, 8×4=32, 32÷4=8, 32÷8=4 are all related. In this problem, we need to find 32÷8 for an array with 32 dots in 8 rows, which means finding dots per row as the missing factor in 8×?=32. Using the missing factor approach: Think: what times 8 equals 32? Answer: 4, because 4×8=32. Choice B is correct because 4×8=32, so 4 is the missing factor that makes 32 when multiplied by 8, which means 32÷8=4. This demonstrates understanding that division finds the unknown factor in multiplication. Choice C is incorrect because it provides 8, which is the number of rows (divisor) instead of solving for the missing factor 4; this error occurs when students confuse the roles of the numbers in the equation or don't connect multiplication to division. To help students understand division as missing factor: Explicitly teach the connection—"32÷8 means: what times 8 equals 32?" Practice fact families: if 7×6=42, then 42÷7=6 (division finds the other factor). Use arrays: "8 rows of how many equals 32 total? 8×?=32" Model thinking aloud: "I need to find 56÷7. I think: 7 times what equals 56? I know 7×8=56, so 56÷7=8." Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if 32÷8=4, check: does 4×8=32? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

3

Solve $24 \div 6$ using a missing factor: $6 \times \ ? = 24$.

3

4

6

18

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like 24÷6, you can think of it as a multiplication question: "What number times 6 equals 24?" or "6 times what number equals 24?" This is the same as solving the equation ?×6=24 or 6×?=24. If you know your multiplication facts, you can use them to divide: Since 4×6=24, then 24÷6=4. The missing factor (4) is the quotient. Fact families show this relationship: 4×6=24, 6×4=24, 24÷4=6, 24÷6=4 are all related. In this problem, we need to solve 24÷6 using the missing factor equation 6×?=24. Using the missing factor approach: We know 6×4=24 from multiplication facts, so 24÷6=4. Choice A is correct because 4×6=24, so 4 is the missing factor that makes 24 when multiplied by 6, which means 24÷6=4. This demonstrates understanding that division finds the unknown factor in multiplication. Choice B is incorrect because it provides 6, which is the known factor (divisor) instead of solving for the missing factor 4; this error occurs when students confuse the roles of the numbers in the equation or don't connect multiplication to division. To help students understand division as missing factor: Explicitly teach the connection—"24÷6 means: what times 6 equals 24?" Practice fact families: if 7×6=42, then 42÷7=6 (division finds the other factor). Use arrays: "6 rows of how many equals 24 total? 6×?=24" Model thinking aloud: "I need to find 56÷7. I think: 7 times what equals 56? I know 7×8=56, so 56÷7=8." Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if 24÷6=4, check: does 4×6=24? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

4

Solve $35 \div 7$ by thinking: $7 \times \ ? = 35$.

4

5

7

42

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like 35÷7, you can think of it as a multiplication question: "What number times 7 equals 35?" or "7 times what number equals 35?" This is the same as solving the equation ?×7=35 or 7×?=35. If you know your multiplication facts, you can use them to divide: Since 5×7=35, then 35÷7=5. The missing factor (5) is the quotient. Fact families show this relationship: 5×7=35, 7×5=35, 35÷5=7, 35÷7=5 are all related. In this problem, we need to solve 35÷7 by thinking 7×?=35. Using the missing factor approach: We know 7×5=35 from multiplication facts, so 35÷7=5. Choice C is correct because 5×7=35, so 5 is the missing factor that makes 35 when multiplied by 7, which means 35÷7=5. This demonstrates understanding that division finds the unknown factor in multiplication. Choice B is incorrect because it provides 42, which might come from multiplying 7×6=42 instead of using the correct fact; this error occurs when students make calculation errors or use wrong numbers. To help students understand division as missing factor: Explicitly teach the connection—"35÷7 means: what times 7 equals 35?" Practice fact families: if 7×6=42, then 42÷7=6 (division finds the other factor). Use arrays: "7 rows of how many equals 35 total? 7×?=35" Model thinking aloud: "I need to find 56÷7. I think: 7 times what equals 56? I know 7×8=56, so 56÷7=8." Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if 35÷7=5, check: does 5×7=35? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

5

Use the fact family with 6, 7, and 42 to find $42 \div 6$.

6

7

8

36

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like 42÷6, you can think of it as a multiplication question: "What number times 6 equals 42?" or "6 times what number equals 42?" This is the same as solving the equation ?×6=42 or 6×?=42. If you know your multiplication facts, you can use them to divide: Since 7×6=42, then 42÷6=7. The missing factor (7) is the quotient. Fact families show this relationship: 7×6=42, 6×7=42, 42÷7=6, 42÷6=7 are all related. In this problem, we need to use the fact family with 6, 7, and 42 to find 42÷6. Using the missing factor approach: From the fact family, since 6×7=42, then 42÷6=7. Choice C is correct because 7×6=42, so 7 is the missing factor that makes 42 when multiplied by 6, which means 42÷6=7. This demonstrates understanding that division finds the unknown factor in multiplication. Choice A is incorrect because it provides 6, which is the divisor instead of solving for the missing factor 7; this error occurs when students confuse the roles of the numbers in the fact family or don't connect multiplication to division. To help students understand division as missing factor: Explicitly teach the connection—"42÷6 means: what times 6 equals 42?" Practice fact families: if 7×6=42, then 42÷7=6 (division finds the other factor). Use arrays: "6 rows of how many equals 42 total? 6×?=42" Model thinking aloud: "I need to find 56÷7. I think: 7 times what equals 56? I know 7×8=56, so 56÷7=8." Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if 42÷6=7, check: does 7×6=42? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

6

Find $56 \div 8$; missing factor: $8 \times \ ? = 56$.

6

7

8

64

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like 56÷8, you can think of it as a multiplication question: "What number times 8 equals 56?" or "8 times what number equals 56?" This is the same as solving the equation ?×8=56 or 8×?=56. If you know your multiplication facts, you can use them to divide: Since 7×8=56, then 56÷8=7. The missing factor (7) is the quotient. Fact families show this relationship: 7×8=56, 8×7=56, 56÷7=8, 56÷8=7 are all related. In this problem, we need to find 56÷8 using the missing factor 8×?=56. Using the missing factor approach: We know 8×7=56 from multiplication facts, so 56÷8=7. Choice C is correct because 7×8=56, so 7 is the missing factor that makes 56 when multiplied by 8, which means 56÷8=7. This demonstrates understanding that division finds the unknown factor in multiplication. Choice D is incorrect because it multiplies 8×8=64 instead of dividing or finding the correct missing factor; this error occurs when students confuse operations or use wrong numbers. To help students understand division as missing factor: Explicitly teach the connection—"56÷8 means: what times 8 equals 56?" Practice fact families: if 7×6=42, then 42÷7=6 (division finds the other factor). Use arrays: "8 rows of how many equals 56 total? 8×?=56" Model thinking aloud: "I need to find 56÷7. I think: 7 times what equals 56? I know 7×8=56, so 56÷7=8." Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if 56÷8=7, check: does 7×8=56? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

7

Emma has 42 stickers in 6 equal groups; what is $42 \div 6$?

6

7

8

36

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like 42÷6, you can think of it as a multiplication question: "What number times 6 equals 42?" or "6 times what number equals 42?" This is the same as solving the equation ?×6=42 or 6×?=42. If you know your multiplication facts, you can use them to divide: Since 7×6=42, then 42÷6=7. The missing factor (7) is the quotient. Fact families show this relationship: 7×6=42, 6×7=42, 42÷7=6, 42÷6=7 are all related. In this problem, we need to find 42÷6 for 42 stickers in 6 equal groups, which means finding stickers per group as the missing factor in 6×?=42. Using the missing factor approach: Think: what times 6 equals 42? Answer: 7, because 7×6=42. Choice A is correct because 7×6=42, so 7 is the missing factor that makes 42 when multiplied by 6, which means 42÷6=7. This demonstrates understanding that division finds the unknown factor in multiplication. Choice B is incorrect because it provides 6, which is the number of groups (divisor) instead of solving for the missing factor 7; this error occurs when students confuse the roles of the numbers in the equation or don't connect multiplication to division. To help students understand division as missing factor: Explicitly teach the connection—"42÷6 means: what times 6 equals 42?" Practice fact families: if 7×6=42, then 42÷7=6 (division finds the other factor). Use arrays: "6 rows of how many equals 42 total? 6×?=42" Model thinking aloud: "I need to find 56÷7. I think: 7 times what equals 56? I know 7×8=56, so 56÷7=8." Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if 42÷6=7, check: does 7×6=42? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

8

Which multiplication equation helps solve $48 \div 6$ as a missing factor?

$6 \times 6 = 48$

$6 \times 8 = 48$

$48 \div 6 = 48$

$48 \times 6 = 8$

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like 48÷6, you can think of it as a multiplication question: "What number times 6 equals 48?" or "6 times what number equals 48?" This is the same as solving the equation ?×6=48 or 6×?=48. If you know your multiplication facts, you can use them to divide: Since 8×6=48, then 48÷6=8. The missing factor (8) is the quotient. Fact families show this relationship: 8×6=48, 6×8=48, 48÷8=6, 48÷6=8 are all related. In this problem, we need to identify which multiplication equation helps solve 48÷6 as a missing factor. Using the missing factor approach: The equation 6×?=48 directly represents the division 48÷6. Choice A is correct because the equation 6×8=48 directly represents the division 48÷6 as a missing factor problem. This demonstrates understanding that division finds the unknown factor in multiplication. Choice B is incorrect because it multiplies 48×6=288 but rearranges the numbers incorrectly and doesn't solve for the missing factor; this error occurs when students confuse operations or use wrong numbers. To help students understand division as missing factor: Explicitly teach the connection—"48÷6 means: what times 6 equals 48?" Practice fact families: if 7×6=42, then 42÷7=6 (division finds the other factor). Use arrays: "6 rows of how many equals 48 total? 6×?=48" Model thinking aloud: "I need to find 56÷7. I think: 7 times what equals 56? I know 7×8=56, so 56÷7=8." Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if 48÷6=8, check: does 8×6=48? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

9

What is $32 \div 8$? Think: what times 8 equals 32?

4

5

8

24

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like 32÷8, you can think of it as a multiplication question: "What number times 8 equals 32?" or "8 times what number equals 32?" This is the same as solving the equation ?×8=32 or 8×?=32. If you know your multiplication facts, you can use them to divide: Since 4×8=32, then 32÷8=4. The missing factor (4) is the quotient. Fact families show this relationship: 4×8=32, 8×4=32, 32÷4=8, 32÷8=4 are all related. In this problem, we need to find 32÷8 by thinking what times 8 equals 32. Using the missing factor approach: Think: what times 8 equals 32? Answer: 4, because 4×8=32. Choice B is correct because 4×8=32, so 4 is the missing factor that makes 32 when multiplied by 8, which means 32÷8=4. This demonstrates understanding that division finds the unknown factor in multiplication. Choice A is incorrect because it provides 8, which is the known factor (divisor) instead of solving for the missing factor 4; this error occurs when students confuse the roles of the numbers in the equation or don't connect multiplication to division. To help students understand division as missing factor: Explicitly teach the connection—"32÷8 means: what times 8 equals 32?" Practice fact families: if 7×6=42, then 42÷7=6 (division finds the other factor). Use arrays: "8 rows of how many equals 32 total? 8×?=32" Model thinking aloud: "I need to find 56÷7. I think: 7 times what equals 56? I know 7×8=56, so 56÷7=8." Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if 32÷8=4, check: does 4×8=32? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

10

A tray has $32$ apples in $8$ rows; use $8 \times ? = 32$.

3

4

8

40

Explanation

This question tests understanding division as an unknown-factor problem (CCSS.3.OA.6), specifically recognizing that division can be solved by finding the missing factor in a multiplication equation. Division and multiplication are inverse operations—they undo each other. When you see a division problem like $32 \div 8$ (apples per row), you can think of it as a multiplication question: 'What number times 8 equals 32?' or '8 times what number equals 32?' This is the same as solving the equation $? \times 8 = 32$ or $8 \times ? = 32$. If you know your multiplication facts, you can use them to divide: Since $4 \times 8 = 32$, then $32 \div 8 = 4$. The missing factor (4) is the quotient. Fact families show this relationship: $4 \times 8 = 32$, $8 \times 4 = 32$, $32 \div 4 = 8$, $32 \div 8 = 4$ are all related. In this problem, we need to find how many apples per row with 32 apples in 8 rows, using $8 \times ? = 32$. Using the missing factor approach: Think: what times 8 equals 32? Answer: 4, because $4 \times 8 = 32$. Choice A is correct because $4 \times 8 = 32$, so 4 is the missing factor that makes 32 when multiplied by 8, which means $32 \div 8 = 4$ apples per row. This demonstrates understanding that division finds the unknown factor in multiplication. Choice C is incorrect because it provides 40, which might come from addition ($32 + 8 = 40$) instead of multiplication/division. This error occurs when students confuse operations. To help students understand division as missing factor: Explicitly teach the connection—'32÷8 means: what times 8 equals 32?' Practice fact families: if $7 \times 6 = 42$, then $42 \div 7 = 6$ (division finds the other factor). Use arrays: '8 rows of how many equals 32 total? $8 \times ? = 32$' Model thinking aloud: 'I need to find $56 \div 7$. I think: 7 times what equals 56? I know $7 \times 8 = 56$, so $56 \div 7 = 8$.' Have students write both equations (division and missing factor multiplication) side by side. Check division answers by multiplying (if $32 \div 8 = 4$, check: does $4 \times 8 = 32$? Yes!). This reinforces the inverse relationship. Watch for students who can multiply but struggle with division—show them they already know division by knowing multiplication facts.

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