Adding and subtracting to a million · Year 5
In Adding and subtracting to a million (Year 5) you practise 4 skills: Column addition and subtraction · Clever strategies · Equations and inequalities · Estimating. In an addition you can take an amount from one number and add the same amount to the other, and the sum does not change. So 3,625 + 1,297 equals 3,622 + 1,300, and the second one is easy to work out in your head.
In a subtraction you can add the same amount to both numbers, or take the same amount from both, and the difference does not change. So 5,000 − 1,998 equals 5,002 − 2,000, which is 3,002. Addition and subtraction undo each other. Use them to check an answer and to find a missing number: if ☐ + 2,500 = 7,000, the missing number is 7,000 − 2,500, which is 4,500.
Tip: Before you work it out, estimate: round the numbers, and at the end check that your answer is close to the estimate.
What you learn
Column addition and subtraction
For example: Work out: 861 + 137
Answer and solution
The answer: 998
Write the numbers one under the other, units under units, and work column by column from the right: 861
+ 137
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998 861 + 137 = 998
Clever strategies
For example: Complete it so that both sides are equal: 57,094 + 6,398 = 57,092 + ☐
Answer and solution
The answer: 6400
We took 2 from the first number and added 2 to the second; the sum did not change: 57,092 + 6,400 = 63,492
Equations and inequalities
For example: Find the missing number: 57,100 + ☐ = 63,100
Answer and solution
The answer: 6000
To find a missing number in a sum, take the known number from the total: 63,100 − 57,100 = 6,000 . Check: 57,100 + 6,000 = 63,100
Estimating
For example: Round 2,288 to the nearest thousand.
Answer and solution
The answer: 2000
The deciding digit is 2, so round down: 2,288 ≈ 2,000
The exercises are made by rules and the answers are worked out in code, so there are new exercises every time. The topic follows the national curriculum in England: mathematics (key stages 3 and 4).