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Subtraction within 100
Taking away within a hundred: small numbers first, then ones and tens, two two-digit numbers and finding how many more.
Choose what to practise
Each round is 10 questions, and takes 5 to 10 minutes.
Finished
Taking away within a hundred: small numbers first, then ones and tens, two two-digit numbers and finding how many more.
Choose what to practise
Each round is 10 questions, and takes 5 to 10 minutes.
Finished
In Year 2, children develop fluency with subtraction facts to 20 and learn to subtract within 100. They practise subtracting ones and tens from two-digit numbers, subtracting two-digit numbers, and finding the difference between two amounts.
Bridge through ten. Breaking a calculation into smaller steps makes mental subtraction easier. To work out 63 − 7, split 7 into 3 and 4: subtract 3 to reach 60, then subtract 4 to get 56.
Subtract tens, then ones. To calculate 62 − 38, subtract 30 to get 32, then subtract 8 in two steps: subtract 2 to reach 30, then 6 more to get 24.
Watch out for reversed digits. Some children calculate 62 − 38 as 36 by subtracting the smaller digit from the larger in each column. Estimating first helps: subtracting 30 from 62 leaves 32, so subtracting 38 must give an answer below 32.
Count up to find the difference. To compare 25 and 18, count from 18 to 20, then to 25. The jumps are 2 and 5, so the difference is 7.
In Year 3, children extend subtraction to three-digit numbers and learn written methods, including column subtraction with exchanging. Understanding place value provides the foundation for this work.