Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 245 · 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. 1.601 − 397 =
2. 2.938 − 279 =
3. 3.283 − 187 =
4. 4.894 − 688 =
5. 5.949 − 619 =
6. 6.889 − 797 =
7. 7.514 − 199 =
8. 8.175 − 148 =
9. 9.550 − 139 =
10. 10.895 − 499 =
11. 11.687 − 129 =
12. 12.616 − 499 =
13. 13.793 − 597 =
14. 14.638 − 599 =
15. 15.882 − 799 =
16. 16.433 − 398 =
17. 17.569 − 199 =
18. 18.887 − 297 =
19. 19.931 − 799 =
20. 20.949 − 419 =
21. 21.907 − 798 =
22. 22.834 − 297 =
23. 23.753 − 319 =
24. 24.511 − 299 =
25. 25.790 − 598 =
26. 26.939 − 399 =
27. 27.713 − 198 =
28. 28.753 − 699 =
29. 29.795 − 118 =
30. 30.860 − 198 =
31. 31.922 − 599 =
32. 32.790 − 307 =
33. 33.402 − 218 =
34. 34.580 − 487 =
35. 35.875 − 457 =
36. 36.870 − 699 =
37. 37.670 − 279 =
38. 38.784 − 499 =
39. 39.738 − 577 =
40. 40.650 − 158 =

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