Two-Digit Addition & Subtraction — Answer Key
Part A: Sort the Words
Sort each word or number into the correct category box.
1. Sort each problem: needs regrouping or no regrouping.
No Regrouping
42+3163+1571+18 Needs Regrouping
56+2738+4529+54 If the ones digits add to 9 or less (like 2+1=3 or 3+5=8), no regrouping is needed. If they add to 10 or more (like 6+7=13 or 8+5=13), you must carry 1 ten over and regroup.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. 87 - 43 = 44.
Subtract the ones first: 7 − 3 = 4. Then subtract the tens: 8 − 4 = 4. So 87 − 43 = 44, with no regrouping needed.
2. 95 - 58 = 37.
Since 5 ones cannot subtract 8 ones, regroup 1 ten into 10 ones: 15 − 8 = 7. Then 8 − 5 = 3 in the tens. The result is 37.
3. 62 - 27 = 35.
To find the missing whole, add the parts: 27 + 35 = 62. Check by subtracting: 62 − 27 = 35.
4. 73 - 46 = 27.
Because 3 ones is less than 6 ones, regroup 1 ten as 10 ones: 13 − 6 = 7. Then the tens become 6 − 4 = 2. So 73 − 46 = 27.
5. 61 - 37 = 24.
To find the missing part, subtract the difference from the whole: 61 − 24 = 37. Check: 61 − 37 = 24.
Part C: True or False?
Read each statement. Circle True or False.
1. 34 + 29 = 63.
True False
Add the ones: 4 + 9 = 13, write 3 and carry 1. Add the tens: 3 + 2 + 1 = 6. The sum is 63, so the equation is true.
2. 81 - 47 = 44.
True False
Regroup: 11 − 7 = 4 in the ones, then 7 − 4 = 3 in the tens. The real answer is 34, not 44.
3. 55 + 36 = 91.
True False
Add the ones: 5 + 6 = 11, write 1 and carry 1. Add the tens: 5 + 3 + 1 = 9. The sum is 91, which matches.
4. 70 - 28 = 48.
True False
Regroup: 10 − 8 = 2 in the ones, then 6 − 2 = 4 in the tens. The correct answer is 42, not 48.