Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 587 · 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. 1.789 − 688 =
2. 2.908 − 569 =
3. 3.852 − 398 =
4. 4.970 − 549 =
5. 5.512 − 397 =
6. 6.852 − 797 =
7. 7.647 − 189 =
8. 8.722 − 599 =
9. 9.990 − 477 =
10. 10.944 − 249 =
11. 11.649 − 597 =
12. 12.740 − 607 =
13. 13.618 − 499 =
14. 14.537 − 449 =
15. 15.848 − 149 =
16. 16.704 − 639 =
17. 17.709 − 498 =
18. 18.714 − 487 =
19. 19.712 − 239 =
20. 20.739 − 698 =
21. 21.642 − 398 =
22. 22.422 − 137 =
23. 23.907 − 658 =
24. 24.694 − 487 =
25. 25.670 − 197 =
26. 26.259 − 198 =
27. 27.981 − 229 =
28. 28.730 − 147 =
29. 29.262 − 198 =
30. 30.880 − 198 =
31. 31.403 − 127 =
32. 32.390 − 199 =
33. 33.301 − 239 =
34. 34.549 − 259 =
35. 35.944 − 599 =
36. 36.535 − 499 =
37. 37.622 − 597 =
38. 38.921 − 178 =
39. 39.632 − 397 =
40. 40.828 − 398 =

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