Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 827 · 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. 1.779 − 397 =
2. 2.867 − 797 =
3. 3.252 − 227 =
4. 4.858 − 798 =
5. 5.448 − 398 =
6. 6.533 − 199 =
7. 7.810 − 298 =
8. 8.396 − 179 =
9. 9.735 − 698 =
10. 10.839 − 297 =
11. 11.844 − 797 =
12. 12.637 − 499 =
13. 13.616 − 229 =
14. 14.595 − 579 =
15. 15.855 − 499 =
16. 16.755 − 559 =
17. 17.533 − 418 =
18. 18.851 − 199 =
19. 19.766 − 397 =
20. 20.822 − 197 =
21. 21.859 − 488 =
22. 22.938 − 598 =
23. 23.791 − 197 =
24. 24.914 − 507 =
25. 25.367 − 169 =
26. 26.946 − 198 =
27. 27.620 − 497 =
28. 28.976 − 198 =
29. 29.688 − 527 =
30. 30.687 − 519 =
31. 31.892 − 797 =
32. 32.864 − 797 =
33. 33.583 − 548 =
34. 34.618 − 598 =
35. 35.445 − 398 =
36. 36.671 − 498 =
37. 37.302 − 208 =
38. 38.594 − 297 =
39. 39.659 − 598 =
40. 40.766 − 699 =

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