How it works
- Choose the exercise and the size of the numbers above, then how many questions: 10, 20, 30 or 40.
- Print the sheet. The answer key comes on a page of its own, so the sheet can be handed out without the answers.
- Or practise on screen. The same questions appear with a box for each answer, and every answer is marked when you check. There is no score and no clock.
- Keep the link. The address holds both the settings and the numbers, so the same link gives the same sheet again.
The three exercises
- Prime factorisation: write 360 as a product of primes. The answer is 2 · 2 · 2 · 3 · 3 · 5, or 2³ · 3² · 5; the key prints the second form. The order does not matter, but a number that is not prime (4 · 9 · 10) is not a factorisation yet.
- Which are prime? Five numbers, of which at least one is prime. Numbers up to 100 or up to 1,000.
- Divisibility rules: which of 2, 3, 5, 9 and 10 divide a number. The rules are the ones taught in years 4–6: last digit for 2, 5 and 10, digit sum for 3 and 9.
On screen, write the factors with a dot between them. 2·2·3, 2^2·3, 2²·3 and 2*2*3 all count.
To factorise any number and see the steps, use the prime factorisation calculator.