Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 26 · 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. 1.851 − 577 =
2. 2.558 − 507 =
3. 3.841 − 699 =
4. 4.608 − 559 =
5. 5.957 − 139 =
6. 6.938 − 299 =
7. 7.881 − 599 =
8. 8.767 − 697 =
9. 9.900 − 498 =
10. 10.638 − 499 =
11. 11.537 − 198 =
12. 12.524 − 299 =
13. 13.809 − 628 =
14. 14.904 − 688 =
15. 15.810 − 398 =
16. 16.722 − 699 =
17. 17.670 − 119 =
18. 18.586 − 197 =
19. 19.910 − 517 =
20. 20.796 − 659 =
21. 21.404 − 317 =
22. 22.701 − 438 =
23. 23.547 − 298 =
24. 24.635 − 599 =
25. 25.368 − 338 =
26. 26.969 − 798 =
27. 27.545 − 399 =
28. 28.972 − 279 =
29. 29.356 − 167 =
30. 30.972 − 367 =
31. 31.394 − 277 =
32. 32.245 − 179 =
33. 33.946 − 399 =
34. 34.996 − 797 =
35. 35.891 − 568 =
36. 36.529 − 197 =
37. 37.668 − 299 =
38. 38.868 − 199 =
39. 39.647 − 597 =
40. 40.394 − 117 =

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