Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 875 · 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. 1.968 − 497 =
2. 2.724 − 609 =
3. 3.875 − 299 =
4. 4.925 − 797 =
5. 5.703 − 299 =
6. 6.974 − 799 =
7. 7.653 − 498 =
8. 8.885 − 259 =
9. 9.781 − 498 =
10. 10.804 − 598 =
11. 11.996 − 558 =
12. 12.362 − 247 =
13. 13.520 − 497 =
14. 14.878 − 597 =
15. 15.891 − 658 =
16. 16.999 − 699 =
17. 17.702 − 539 =
18. 18.903 − 197 =
19. 19.981 − 797 =
20. 20.987 − 699 =
21. 21.895 − 599 =
22. 22.636 − 299 =
23. 23.896 − 288 =
24. 24.385 − 197 =
25. 25.636 − 119 =
26. 26.822 − 797 =
27. 27.684 − 398 =
28. 28.977 − 198 =
29. 29.502 − 197 =
30. 30.893 − 289 =
31. 31.989 − 597 =
32. 32.673 − 198 =
33. 33.558 − 299 =
34. 34.506 − 248 =
35. 35.471 − 197 =
36. 36.430 − 199 =
37. 37.800 − 298 =
38. 38.941 − 399 =
39. 39.996 − 497 =
40. 40.551 − 508 =

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