Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 719 · 40 questions

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

1. 1.926 − 389 =
2. 2.913 − 797 =
3. 3.506 − 209 =
4. 4.851 − 549 =
5. 5.906 − 667 =
6. 6.893 − 577 =
7. 7.624 − 398 =
8. 8.777 − 198 =
9. 9.433 − 299 =
10. 10.821 − 397 =
11. 11.534 − 299 =
12. 12.808 − 599 =
13. 13.493 − 398 =
14. 14.715 − 439 =
15. 15.772 − 389 =
16. 16.217 − 198 =
17. 17.815 − 798 =
18. 18.660 − 258 =
19. 19.767 − 408 =
20. 20.439 − 299 =
21. 21.900 − 539 =
22. 22.295 − 147 =
23. 23.892 − 419 =
24. 24.478 − 399 =
25. 25.969 − 678 =
26. 26.760 − 398 =
27. 27.315 − 229 =
28. 28.350 − 298 =
29. 29.871 − 519 =
30. 30.579 − 397 =
31. 31.389 − 199 =
32. 32.813 − 697 =
33. 33.999 − 799 =
34. 34.955 − 618 =
35. 35.667 − 538 =
36. 36.942 − 699 =
37. 37.643 − 479 =
38. 38.682 − 399 =
39. 39.798 − 699 =
40. 40.922 − 797 =

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