Jump by Tens: 10 More and 10 Less - 1st Grade Math

SECTION 1

Why We Count by Tens

Long ago, people needed to count things like sheep, apples, and coins. They looked at their hands and saw ten fingers. This made ten a very special number! People all around the world started using ten as a way to count bigger numbers.

Ancient Times • Finger Counting

People used their ten fingers to count. This is why we have a base-ten system today.

Egypt • Ten Symbols

Ancient Egyptians made special symbols for ten, one hundred, and one thousand. They loved counting by tens!

China • Abacus Counting

Chinese people made the abacus with ten beads on each row. This helped them jump by tens very quickly.

Today • Modern Math

We still use ten as our counting base. Learning to add and subtract ten helps us with bigger math problems.

Today, we learn to jump by tens because it makes counting faster and easier. When we know how to find 10 more or 10 less than any number, we can solve math problems much quicker!

SECTION 2

Core Principles of Jumping by Tens

Learning to jump by tens means we can quickly find numbers that are 10 more or 10 less than any starting number. This skill helps us count faster and understand how our number system works.

Ten More Pattern

When we add 10 to any number, only the tens digit changes. The ones digit stays the same. For example: 23 + 10 = 33.

Ten Less Pattern

When we subtract 10 from any number, only the tens digit changes. The ones digit stays the same. For example: 67 - 10 = 57.

Number Line Jumps

On a number line, jumping by ten means we hop over nine numbers to land exactly ten spaces away from where we started.

Quick Counting

Instead of counting one by one (1, 2, 3...), we can count by tens to reach bigger numbers faster: 10, 20, 30, 40, 50...

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KEY TAKEAWAY

Think of jumping by tens like climbing stairs ten steps at a time! If you're on step 25 and jump up ten steps, you land on step 35. If you jump down ten steps, you land on step 15. The last number stays the same (the 5), but the first number changes (2 becomes 3 or 1).

SECTION 3

Visualizing Ten More and Ten Less

The number line shows how we can jump from 43 to 33 (10 less) or to 53 (10 more). The base-ten blocks help us see that adding or subtracting 10 means adding or removing one ten-block while keeping the same number of ones.

This diagram shows us two important ways to think about jumping by tens. On the number line, we can see that 43 jumps to 33 when we go ten less, and jumps to 53 when we go ten more. The base-ten blocks help us understand that we're really just adding or taking away one group of ten, while the three ones stay exactly the same.

SECTION 4

Mathematical Framework

The math behind jumping by tens follows simple patterns that we can write as equations. These equations help us see exactly what happens when we add or subtract ten from any number.

TEN MORE

Any Number + 10 = New Number

When we add 10 to any number, the tens digit goes up by 1 and the ones digit stays the same. For example: 27 + 10 = 37.

TEN LESS

Any Number − 10 = New Number

When we subtract 10 from any number, the tens digit goes down by 1 and the ones digit stays the same. For example: 85 − 10 = 75.

PLACE VALUE RULE

Tens Place ± 1, Ones Place = Same

The place value system helps us understand that adding or subtracting 10 only affects the tens place, never the ones place.

These simple rules work for any two-digit number! Whether we start with 14, 39, 62, or 98, the pattern is always the same. The magic happens because our number system groups everything by tens.

SECTION 5

Number Patterns and Sequences

When we jump by tens, we create beautiful number patterns. These patterns help us see how numbers are organized and make counting much easier.

The hundreds chart shows how numbers in the same column are always 10 apart. Look at the yellow column: 1, 11, 21, 31, 41... Each number is exactly 10 more than the one above it!

The hundreds chart is like a map for numbers! When we look at any column going down, we're always adding 10. When we look at any column going up, we're always subtracting 10. This pattern works for every single column on the chart!

SECTION 6

Step-by-Step Example

Let's work through a complete example together! We'll start with the number 67 and find both 10 more and 10 less.

Finding 10 More and 10 Less than 67

1
Step 1 — Look at the Starting Number

Our starting number is 67. This means we have 6 tens and 7 ones. We can write this as 60 + 7 = 67.

67 = 6 tens + 7 ones
2
Step 2 — Find 10 More

To find 10 more, we add 10 to our number: 67 + 10. This means we add one more ten to our 6 tens. The 7 ones stay the same!

67 + 10 = 77
3
Step 3 — Find 10 Less

To find 10 less, we subtract 10 from our number: 67 − 10. This means we take away one ten from our 6 tens. The 7 ones stay the same!

67 − 10 = 57
4
Step 4 — Check Our Pattern

Let's make sure our answers follow the pattern. In 57, 67, and 77, the ones digit is always 7, and only the tens digit changes: 5, 6, 7.

Pattern confirmed: 57, 67, 77

SECTION 7

Helpful Strategies and Tips

There are several strategies we can use to make jumping by tens even easier. Some work better for different students, so try them all and see which ones you like best!

Strategy	How It Works	Example
Finger Counting	Use your fingers to count by tens. Each finger represents 10.	25 + 10: Start at 25, put up one finger, end at 35
Number Line Hops	Draw or imagine a number line and make big hops of 10.	48 − 10: Hop backwards from 48 to 38
Tens Place Focus	Only look at the tens digit and add or subtract 1.	84 + 10: Change the 8 to 9, keep the 4. Answer: 94
Base-Ten Blocks	Use blocks to show adding or removing a group of ten.	32 + 10: Add one ten-block to 3 tens and 2 ones

Different strategies for jumping by tens

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KEY TAKEAWAY

Think of the tens digit like a floor number in an elevator! When you go up 10, you go up one floor. When you go down 10, you go down one floor. The ones digit is like your room number on that floor - it never changes when you're just moving between floors!

SECTION 8

Working with Bigger Numbers

The same rules for jumping by tens work with bigger numbers too! Even though first graders usually work with numbers up to 100, it's fun to see how our pattern keeps working with larger numbers.

Number Type	Example	10 More	10 Less
Two-digit numbers	45	55	35
Three-digit numbers	123	133	113
Numbers ending in 9	89	99	79
Numbers ending in 0	90	100	80

Jumping by tens works with all kinds of numbers!

As you get older and learn about hundreds and thousands, you'll discover that this same pattern keeps working! The ones digit always stays the same, and only the tens digit changes. This makes jumping by tens one of the most useful math skills you'll ever learn.

SECTION 9

Practice Problems

Now it's time to practice! These problems will help you become a jumping by tens expert. Start with the easier ones and work your way up to the harder ones.

Question 1: CONCEPTUAL

When we add 10 to any number, which digit changes: the tens digit or the ones digit?

Show answer

The tens digit changes when we add 10 to any number. The ones digit stays exactly the same. This happens because 10 is made up of 1 ten and 0 ones, so we're only adding to the tens place. For example, when we add 10 to 34, we get 44 - the 3 becomes 4, but the ones digit stays as 4.

Question 2: BASIC CALCULATION

Find 10 more than 26.

Show answer

36. To find 10 more than 26, I add 10: 26 + 10 = 36. I can see this works because the ones digit stays 6, and the tens digit changes from 2 to 3. I could also think of it as 2 tens and 6 ones becoming 3 tens and 6 ones.

Question 3: INTERMEDIATE

What number is 10 less than 73? What number is 10 more than 73? Show both answers.

Show answer

10 less than 73 is 63, and 10 more than 73 is 83. For 10 less: 73 − 10 = 63 (the 7 becomes 6, the 3 stays the same). For 10 more: 73 + 10 = 83 (the 7 becomes 8, the 3 stays the same). This creates a pattern: 63, 73, 83, where all three numbers end in 3.

Question 4: APPLIED

Sarah has 48 stickers. Her friend gives her 10 more stickers. Then Sarah gives 10 stickers to her brother. How many stickers does Sarah have now?

Show answer

Sarah has 48 stickers. First, she gets 10 more: 48 + 10 = 58 stickers. Then she gives away 10: 58 − 10 = 48 stickers. Sarah ends up with 48 stickers, the same amount she started with! This makes sense because adding 10 and then subtracting 10 brings us back to where we started.

Question 5: CRITICAL THINKING

Look at this pattern: 15, 25, 35, 45. What comes next? What comes before 15? Explain the pattern.

Show answer

The next number is 55, and the number before 15 is 5. This pattern shows counting by tens, where each number is 10 more than the one before it. All numbers end in 5 (the ones digit), while the tens digit goes up by 1 each time: 0, 1, 2, 3, 4, 5. This is a perfect example of how jumping by tens creates predictable patterns where the ones digit stays the same.

SUMMARY

Key Points Review

Summary

Learning to jump by tens is one of the most important math skills for first graders. When we add 10 to any number, only the tens digit changes and the ones digit stays the same. The same rule works when we subtract 10 - only the tens digit gets smaller while the ones digit stays put.

We can use many helpful strategies like finger counting, number line hops, and base-ten blocks. This skill helps us count faster, understand number patterns, and prepares us for bigger math problems in the future. Remember: jumping by tens is like taking the elevator between floors - you change floors (tens) but your room number (ones) stays the same!