Two Digit Addition and Subtraction

Grade 2 · Math · Study Guide

Learn how to add and subtract two-digit numbers using place value.

When we add or subtract two-digit numbers, we think about the tens place and the ones place separately.

A two-digit number has two parts: tens and ones. For example, the number 47 has 4 tens and 7 ones. When we add numbers like 23 + 14, we add the ones first (3 + 4 = 7), then add the tens (2 + 1 = 3), giving us 37.

Sometimes when we add the ones, we get 10 or more. This is called regrouping or carrying. For example, 28 + 15: the ones are 8 + 5 = 13. We write 3 in the ones place and carry 1 ten to the tens place. Then 2 + 1 + 1 = 4 tens. The answer is 43.

For subtraction, we also work with tens and ones. In 56 - 23, we subtract the ones first (6 - 3 = 3), then the tens (5 - 2 = 3), giving us 33.

Sometimes we need to regroup when subtracting too. If the top ones digit is smaller than the bottom ones digit, we borrow 1 ten from the tens place. Practice makes this easier and more fun!

Key terms

Tens place
The place value that tells how many groups of ten are in a number
Ones place
The place value that tells how many single units are in a number
Regrouping
Moving a group of 10 ones to the tens place (or borrowing a ten) when adding or subtracting
Sum
The answer when you add two or more numbers together
Difference
The answer when you subtract one number from another
Carry
To move a value from the ones column to the tens column when the sum is 10 or more

Flashcards

23 + 14 = ?
37
45 + 32 = ?
77
56 - 23 = ?
33
70 - 40 = ?
30
28 + 15 = ?
43 (regroup the ones)
63 - 27 = ?
36 (regroup the tens)
Tens place in 58
5 (meaning 5 tens = 50)
Ones place in 47
7

Questions

  1. What is 34 + 25?

    1. 57
    2. 59
    3. 61
    4. 49
    Show answer

    Answer: 59

    Add ones: 4 + 5 = 9. Add tens: 3 + 2 = 5. So 34 + 25 = 59.

  2. When you add 47 + 36, you need to regroup the ones.

    Show answer

    Answer: True

    7 + 6 = 13, which is more than 9, so we regroup by carrying 1 ten.

  3. 65 - 32 = ___

    Show answer

    Answer: 33

    Subtract ones: 5 - 2 = 3. Subtract tens: 6 - 3 = 3. So 65 - 32 = 33.

  4. What is 18 + 27?

    1. 35
    2. 44
    3. 45
    4. 46
    Show answer

    Answer: 45

    Add ones: 8 + 7 = 15, write 5 carry 1. Add tens: 1 + 2 + 1 = 4. So 18 + 27 = 45.

  5. In the number 72, the digit 7 is in the ones place.

    Show answer

    Answer: False

    In 72, the digit 7 is in the tens place (meaning 70), and 2 is in the ones place.

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