Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 270 · 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. 1.845 − 698 =
2. 2.673 − 438 =
3. 3.826 − 308 =
4. 4.641 − 599 =
5. 5.790 − 168 =
6. 6.982 − 497 =
7. 7.314 − 197 =
8. 8.684 − 538 =
9. 9.492 − 389 =
10. 10.826 − 398 =
11. 11.844 − 599 =
12. 12.910 − 279 =
13. 13.719 − 459 =
14. 14.537 − 497 =
15. 15.874 − 298 =
16. 16.561 − 479 =
17. 17.436 − 408 =
18. 18.867 − 627 =
19. 19.470 − 449 =
20. 20.730 − 139 =
21. 21.548 − 417 =
22. 22.770 − 498 =
23. 23.422 − 198 =
24. 24.907 − 598 =
25. 25.927 − 697 =
26. 26.896 − 698 =
27. 27.763 − 299 =
28. 28.876 − 399 =
29. 29.860 − 599 =
30. 30.877 − 597 =
31. 31.819 − 797 =
32. 32.681 − 299 =
33. 33.843 − 699 =
34. 34.875 − 197 =
35. 35.922 − 218 =
36. 36.875 − 599 =
37. 37.686 − 597 =
38. 38.994 − 599 =
39. 39.866 − 119 =
40. 40.899 − 798 =

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