Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 459 · 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. 1.831 − 699 =
2. 2.668 − 447 =
3. 3.891 − 498 =
4. 4.788 − 119 =
5. 5.854 − 198 =
6. 6.586 − 198 =
7. 7.865 − 289 =
8. 8.529 − 397 =
9. 9.715 − 658 =
10. 10.342 − 178 =
11. 11.991 − 549 =
12. 12.861 − 468 =
13. 13.730 − 697 =
14. 14.529 − 478 =
15. 15.436 − 299 =
16. 16.538 − 498 =
17. 17.813 − 799 =
18. 18.505 − 299 =
19. 19.357 − 198 =
20. 20.636 − 428 =
21. 21.918 − 197 =
22. 22.699 − 199 =
23. 23.409 − 268 =
24. 24.351 − 268 =
25. 25.417 − 179 =
26. 26.755 − 398 =
27. 27.462 − 347 =
28. 28.974 − 498 =
29. 29.790 − 499 =
30. 30.602 − 298 =
31. 31.791 − 599 =
32. 32.665 − 499 =
33. 33.913 − 698 =
34. 34.709 − 207 =
35. 35.585 − 197 =
36. 36.887 − 698 =
37. 37.804 − 679 =
38. 38.790 − 699 =
39. 39.536 − 127 =
40. 40.714 − 647 =

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