Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 403 · 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. 1.407 − 297 =
2. 2.650 − 497 =
3. 3.418 − 397 =
4. 4.474 − 129 =
5. 5.612 − 598 =
6. 6.784 − 618 =
7. 7.303 − 197 =
8. 8.670 − 299 =
9. 9.934 − 397 =
10. 10.886 − 799 =
11. 11.751 − 599 =
12. 12.416 − 218 =
13. 13.643 − 297 =
14. 14.992 − 399 =
15. 15.715 − 498 =
16. 16.767 − 699 =
17. 17.840 − 497 =
18. 18.680 − 199 =
19. 19.795 − 549 =
20. 20.310 − 199 =
21. 21.951 − 119 =
22. 22.386 − 289 =
23. 23.607 − 477 =
24. 24.379 − 197 =
25. 25.749 − 699 =
26. 26.862 − 397 =
27. 27.749 − 117 =
28. 28.569 − 498 =
29. 29.956 − 397 =
30. 30.917 − 599 =
31. 31.709 − 467 =
32. 32.380 − 197 =
33. 33.443 − 398 =
34. 34.894 − 298 =
35. 35.678 − 597 =
36. 36.539 − 199 =
37. 37.897 − 298 =
38. 38.694 − 559 =
39. 39.516 − 197 =
40. 40.362 − 198 =

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