LOOP Send feedback
Homeschool math, Grade 2, adding two-digit numbers

Why does my child forget to carry the one?

46 plus 27 answered 613 in pencil: each column added, the ten never carried.

For example: 46 + 27 = 613

The right answer is 73. Your child wrote 63 or 613 because they added each column and never carried the ten from the ones. Lots of kids do this. It's fixable, and you can start tonight. In LOOP we call it "Forgot to carry/borrow (adding)."

Your child isn't being careless. Adding each column on its own works until a column adds up to ten or more. Here 6 + 7 is 13, and that's where it breaks.

What they wrote46+ 2763
The right answer46+ 2773
Here is what happened. They added the ones and got 6 + 7 = 13. That 13 doesn't fit in one box. They either wrote just the 3 and dropped the ten, or wrote all of 13. Then they added the tens as 4 + 2 = 6. The answer came out 63, or 613 if they kept the whole 13.

Here is the right way. 6 ones plus 7 ones is 13 ones. That's 1 ten and 3 ones. Write the 3 in the ones place and carry the 1 ten over to the tens. Now the tens are 4 + 2 + 1 = 7, so the answer is 73. Teachers call the trade "carrying."

Is it this, or something else?

Before you fix anything, look at what they actually wrote.

63 or 613Forgot to carry/borrow (adding). This is the page you're on.
730Columns didn't line up. The answer is shifted a place, so the digits are right but the number is ten times too big.
72Their method is fine; one fact slipped. Check which fact: 6 + 7 is the usual one.

One wrong answer might just be a slip. If the same thing shows up again and again, it isn't. The sheet below will show you whether this is a pattern.

Free printable: 12 problems

Two of these (41+32 and 52+25) need no carrying, so they are your check. If those two come back right and the other ten are wrong, this is probably the mistake. Check the key below for the exact wrong answers.

It prints on its own page.

Answer key

1. 73, 2. 63, 3. 73, 4. 73, 5. 63, 6. 63, 7. 91, 8. 77, 9. 83, 10. 65, 11. 82, 12. 85.

A child making this mistake will write one of these for problems 1, 2, 3, 5, 6, 7, 9, 10, 11, 12: 63 or 613, 53 or 513, 63 or 613, 53 or 513, 53 or 513, 81 or 811, 73 or 713, 55 or 515, 72 or 712, 75 or 715. The short ones are exactly 10 less than the true answer. Problems 4 and 8 stay correct.

Adding with carrying
Name ____________Date ________Add. Use a pencil.
1.46+ 27
2.38+ 25
3.57+ 16
4.41+ 32
5.29+ 34
6.18+ 45
7.67+ 24
8.52+ 25
9.35+ 48
10.26+ 39
11.54+ 28
12.49+ 36
looplearning.org

What to do this week

  1. Day 1: Use dimes and pennies, or base-ten blocks if you have them. Lay out 46 as 4 dimes and 6 pennies, and 27 as 2 dimes and 7 pennies. Ask your child to push all the pennies together and count them. They'll have 13 pennies. Pause there, and don't tell them what to do. If they get stuck, ask what 10 pennies can turn into. Once they trade 10 pennies for a dime, they have 3 pennies and 7 dimes, and the answer is 73.
  2. Day 2: Same problems, now on paper. After each ones column, have them say out loud: "Did the ones make ten or more?" In 46 + 27, 6 + 7 is 13. Is that ten or more? Yes, so carry the ten before you add the tens.
  3. Day 3: Do the printable again and count how many of the ten are still wrong. If most are right now, you're good. If they're still getting the same wrong answer, do Day 1 again.

LOOP does this for every page. Your child does a printed page in pencil. You take a photo. LOOP tells you which mistake showed up on each problem and prints the next page. Your child works on paper the whole time.

Sign up

Tyler Judson, LOOP co-founder. Before LOOP I tutored math, one kid at a time. LOOP is my try at giving every kid that kind of attention without a tutor in the room.

The mistake names are the ones LOOP uses, examples checked by running LOOP's mistake-finder.

Know what your child is missing, on paper.

Sign up