Adding and Subtracting Two Digit Numbers
Adding and Subtracting Two Digit Numbers is the Year 2 skill of using the formal column method to add or subtract two two-digit numbers, working through carrying, regrouping ten ones into one ten, or exchanging, breaking one ten into ten ones, whenever a column will not work without it.
Before you start
Make sure you're comfortable with these topics first:
Method
- Rebuild both numbers with base-10 blocks first, as a stack of ten-rods for the tens and single cubes for the ones, so the child sees a two-digit number as a physical amount before any columns are drawn.
- Set the written calculation out in columns, with the ones digits lined up directly under each other and the tens digits lined up directly under each other, and a plus or minus sign to the left.
- For addition, always add the ones column first. If the ones total is 10 or more, write down only the ones digit of that total and carry the ten into the tens column as a small '1' above the tens digits.
- Add the tens column next, remembering to include any carried ten, and write the final tens digit.
- For subtraction, always subtract the ones column first. If the top ones digit is smaller than the ones digit being taken away, exchange one ten from the tens column for ten extra ones, cross out the original tens digit and write one less above it, then subtract the ones as normal.
- Subtract the tens column next, using the reduced tens digit from any exchange, to complete the answer.
- Check every column answer using base-10 blocks or a quick mental estimate (rounding both numbers to the nearest ten first), since a single missed carry or exchange changes the final answer completely.
Worked example
Work out 53 - 26 using the column method.
- Set the numbers out in columns: 53 on top, 26 underneath, ones under ones and tens under tens.
- Look at the ones column: 3 - 6. Since 3 is smaller than 6, exchange one ten from the tens column for ten extra ones: 53 becomes 4 tens and 13 ones.
- Now subtract the ones: 13 - 6 = 7.
- Subtract the tens, using the reduced tens digit: 4 - 2 = 2.
- Combine the two answers: 53 - 26 = 27.
Practice questions
Type your answer and press Check to be marked straight away, or reveal the answer and mark yourself.
Q1In the sum 38 + 45, what do you write in the ones column first: 3, 8, or the total of 8 + 5?Show answer
Answer: The total of 8 + 5 (which is 13, so you write 3 and carry the 1 ten)
Q2Work out 27 + 35 using the column method.Show answer
Answer: 62 (ones: 7 + 5 = 12, write 2 carry 1; tens: 2 + 3 + 1 = 6, so 62)
Q3Work out 61 - 34 using the column method.Show answer
Answer: 27 (ones: 1 - 4 needs exchanging a ten, so 11 - 4 = 7; tens: 5 - 3 = 2, so 27)
Q4Work out 49 + 26 using the column method.Show answer
Answer: 75 (ones: 9 + 6 = 15, write 5 carry 1; tens: 4 + 2 + 1 = 7, so 75)
Q5Work out 72 - 48 using the column method.Show answer
Answer: 24 (ones: 2 - 8 needs exchanging a ten, so 12 - 8 = 4; tens: 6 - 4 = 2, so 24)
Q6A class has 26 pupils. Another class has 38 pupils. How many pupils are there in both classes altogether? Use the column method.Show answer
Answer: 64 pupils (ones: 6 + 8 = 14, write 4 carry 1; tens: 2 + 3 + 1 = 6, so 64)
Exam-style questions
Written in the style of a KS1 Maths exam paper, with a full mark scheme.
Work out 56 + 27 using the column method. Show your working.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 2 available
Work out 82 - 57 using the column method. Show your working.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 2 available
Jamal works out 64 - 39 and writes the answer as 35, by calculating 9 - 4 = 5 in the ones column instead of exchanging a ten. Explain the mistake Jamal has made, and give the correct answer.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 3 available
Free printable worksheet
Want more practice on paper? Download the adding and subtracting two digit numbers worksheet pack - 7 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
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