11 maths adding and subtracting decimals practice
21 October 2026
Adding and subtracting decimals for 11+ maths
Adding and subtracting decimals is a key skill for the 11+ exam. Mastering this helps children solve a range of questions with confidence and accuracy.
Why practice matters
Regular practice with decimal calculations builds strong number sense. Children who are confident with decimals find it easier to tackle word problems and more advanced maths topics.
Worked example: adding decimals
Let's add 3.45 and 2.7.
Step 1: Line up the decimal points so the digits are in the correct columns.
Step 2: Add extra zeros if needed to make the numbers the same length: 3.45 + 2.70.
Step 3: Add the numbers column by column, starting from the right.
5 + 0 = 5 4 + 7 = 11 (write 1, carry 1) 3 + 2 + 1 (carried) = 6
The correct answer is 6.15.
Worked example: subtracting decimals
Let's subtract 1.6 from 4.25.
Step 1: Line up the decimal points: 4.25 - 1.60.
Step 2: Subtract column by column, starting from the right.
5 - 0 = 5
2 - 6 cannot do, so borrow 1 from the 4 (now 3), making 2 become 12.
12 - 6 = 6
3 - 1 = 2
The correct answer is 2.65.
Practical tip for parents
Encourage your child to write out each step and double-check that the decimal points are lined up. Small slips here can lead to incorrect answers, even if the calculation is correct.
Key insight: Lining up decimal points is essential for accuracy when adding and subtracting decimals. This simple habit prevents common mistakes and builds confidence.
