Intro to Regrouping (When Adding & Subtracting)

Answers will vary. The total amount should be 88.

10 ones blocks are equal to 1 tens block.

Yes, I can exchange 50 of them for 5 tens blocks. Then I have 2 ones blocks left over.

2 tens blocks plus 1 tens block is 3 tens blocks. 6 ones blocks plus 3 ones blocks is 9 ones blocks. 3 tens blocks and 9 ones blocks is 39, so 26 + 13 = 39.

I can show 38 as 3 tens blocks and 8 ones blocks. 24 is 2 tens blocks and 4 ones blocks. I take away 2 tens from 3. 1 ten is left. I take away 4 ones from 8. 4 ones are left. I have 1 ten and 4 ones left, which is 14. 38 – 24 = 14.

Yes! After adding, I have 3 tens blocks and 10 ones blocks. 10 ones blocks can be regrouped into 1 tens block, so I have 4 tens blocks, or 40.

No. 7 is greater than 2, so to subtract the ones, I can subtract 7 – 2. 4 is also greater than 1 so to subtract the tens, I can subtract 4 – 1. The answer is 35.

Yes. 7 is less than 9, so I cannot subtract 7 – 9. I have to borrow a ten and regroup it as 10 ones. I take one of the 4 tens blocks and regroup it into 10 ones blocks. Now I have 3 tens blocks and 17 ones block. I need to subtract 1 ten and 9 ones. To subtract the ones, I can subtract 17 – 9. To subtract the tens, I can subtract 3 – 1. The answer is 28.

Cathy got the right answer, but she did not have to regroup the two numbers into ones blocks first. She could have added together the tens and the ones, and then regrouped 10 of the ones into 1 ten.

It does not help to regroup parts of 27. He should regroup 1 ten from 34 into 10 ones, because he needs more than 4 ones.