Addition and Subtraction with Regrouping for Grade 2

Regrouping helps students work with larger numbers by moving value between tens and ones. In Grade 2, this means making a new ten when adding or breaking a ten apart when subtracting.

What Regrouping Means

Regrouping happens when the ones place needs to change. In addition, 10 ones can be grouped into 1 ten. In subtraction, 1 ten can be broken into 10 ones.

This works because place value tells us that 10 ones and 1 ten are worth the same amount.

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Example If 8 ones + 7 ones = 15 ones, that is 1 ten and 5 ones.

Add by Making a New Ten

Try 27 + 15. Start with the ones: 7 + 5 = 12 ones. Regroup 10 of those ones as 1 new ten. Now you have 2 ones left? No. You have 12 ones, which is 1 ten and 2 ones.

Then add the tens: 2 tens + 1 ten + 1 regrouped ten = 4 tens. The answer is 42.

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Example 27 + 15 = 42.

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Tip Say the regrouping out loud: "12 ones is 1 ten and 2 ones."

Subtract by Breaking a Ten

Try 43 - 18. You cannot take 8 ones away from 3 ones, so regroup 1 ten as 10 ones. Now 43 becomes 3 tens and 13 ones.

Subtract the ones first: 13 - 8 = 5. Then subtract the tens: 3 tens - 1 ten = 2 tens. The answer is 25.

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Example 43 - 18 = 25.

Use Regrouping in Word Problems

Regrouping shows up in story problems too. If a class has 36 markers and buys 27 more, students need to add across tens and ones. If 52 stickers are shared and 19 are used, students need to regroup to subtract.

Always decide whether the story is asking you to put together or take away first, then solve carefully.

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Example 36 + 27 = 63 markers in all.

📝 Key Vocabulary

Regrouping

Changing 10 ones into 1 ten, or 1 ten into 10 ones

Tens

Groups of ten ones

Ones

Single units

📐 Standards Alignment

2.NBT.B.5 CCSS.MATH

Fluently add and subtract within 100 using strategies based on place value and properties of operations.

2.NBT.B.9 CCSS.MATH

Explain why addition and subtraction strategies work using place value and operation properties.

🔗 Glossary Connections

Regrouping Regrouping means trading 10 ones for 1 ten, or 1 ten for 10 ones. Place Value Place value tells us what a digit is worth because of where it is in the number. Tens Tens are bundles made from 10 ones. Ones Ones are single things that have not been grouped into a ten.

⚠️ Common Mistakes to Watch For

Forgetting to add the regrouped ten in an addition problem
Subtracting the tens before regrouping the ones
Writing the regrouped 1 in the wrong place

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Real-World Connection Regrouping is useful when adding prices, counting class supplies, or figuring out how many items are left after some are used.

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Fun Fact! Regrouping is sometimes called "carrying" or "borrowing," but place-value language explains what is really happening better.