You have learned before that 10 ones is equal to 1 ten. When you add, you can regroup 1 ten as 10 ones. When you subtract, you can regroup 10 ones as 1 ten.

**To better understand Regrouping when Adding & Subtracting…**

## LET’S BREAK IT DOWN!

### Place value

Place value tells us the value of each digit based on its position in a number. For example, 39 has 3 in the tens place and 9 in the ones place.

### What is regrouping?

When we have more than 10 ones, we can regroup some of them to make a ten. For example, if we have 13 ones, we can regroup them as 1 ten and 3 ones.

### Regroup 53

53 is 5 tens and 3 ones. We can regroup 1 ten as 10 ones. 53 is 4 tens and 13 ones. 53 is also 53 ones. We can regroup 10 ones as 1 ten. 53 is 1 ten and 43 ones.

### Regroup when adding

Add 36 + 25. Add the ones: 6 ones + 5 ones = 11 ones. Regroup 11 ones to make 1 ten and 1 one. Add the tens: 3 + 2 = 5 tens. 5 tens + 1 ten + 1 one is 6 tens and 1 one, or 61. 36 + 25 = 61.

### Regroup when subtracting

Subtract 42 – 15. Try to subtract the ones. We can't take away 5 ones from 2 ones! Regroup 1 ten in 42 into 10 ones. Now we have 12 ones. 12 – 5 = 7 ones. Subtract the remaining tens. 3 tens – 1 ten = 2 tens. There are 2 tens and 7 ones left, or 27. 42 – 15 = 27.

## INTRO TO REGROUPING (WHEN ADDING & SUBTRACTING) VOCABULARY

## INTRO TO REGROUPING (WHEN ADDING & SUBTRACTING) DISCUSSION QUESTIONS

### Do you need to regroup when you add 25 + 15?

### Do you need to regroup to subtract 47 – 12?

### Do you need to regroup to subtract 47 – 19?

### Cathy wanted to add 28 + 43, so she regrouped everything into ones blocks and counted 71 blocks in all. She then regrouped them again into 7 tens blocks and 1 ones block. Did she get the right answer? Did she do it right?

### Joey wanted to subtract 34 – 27, so he took 27 and regrouped one of the tens into 10 ones. What did he do wrong?

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