Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 455 · 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. 1.956 − 498 =
2. 2.884 − 397 =
3. 3.690 − 199 =
4. 4.833 − 529 =
5. 5.817 − 599 =
6. 6.741 − 208 =
7. 7.779 − 149 =
8. 8.320 − 228 =
9. 9.956 − 499 =
10. 10.929 − 497 =
11. 11.723 − 297 =
12. 12.403 − 199 =
13. 13.417 − 197 =
14. 14.698 − 418 =
15. 15.453 − 358 =
16. 16.635 − 598 =
17. 17.858 − 797 =
18. 18.994 − 697 =
19. 19.546 − 397 =
20. 20.899 − 199 =
21. 21.291 − 199 =
22. 22.715 − 599 =
23. 23.712 − 438 =
24. 24.536 − 219 =
25. 25.706 − 599 =
26. 26.733 − 699 =
27. 27.800 − 398 =
28. 28.645 − 568 =
29. 29.413 − 199 =
30. 30.828 − 597 =
31. 31.648 − 399 =
32. 32.553 − 197 =
33. 33.470 − 198 =
34. 34.867 − 497 =
35. 35.908 − 397 =
36. 36.886 − 299 =
37. 37.763 − 397 =
38. 38.961 − 498 =
39. 39.701 − 278 =
40. 40.630 − 517 =

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