Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 939 · 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. 1.940 − 397 =
2. 2.985 − 798 =
3. 3.642 − 198 =
4. 4.437 − 307 =
5. 5.573 − 398 =
6. 6.952 − 139 =
7. 7.390 − 197 =
8. 8.922 − 797 =
9. 9.499 − 118 =
10. 10.991 − 368 =
11. 11.648 − 197 =
12. 12.943 − 797 =
13. 13.403 − 358 =
14. 14.655 − 179 =
15. 15.992 − 598 =
16. 16.563 − 497 =
17. 17.779 − 699 =
18. 18.378 − 297 =
19. 19.496 − 478 =
20. 20.766 − 197 =
21. 21.827 − 797 =
22. 22.748 − 699 =
23. 23.398 − 198 =
24. 24.960 − 599 =
25. 25.349 − 197 =
26. 26.566 − 499 =
27. 27.825 − 588 =
28. 28.820 − 198 =
29. 29.923 − 699 =
30. 30.947 − 297 =
31. 31.959 − 298 =
32. 32.847 − 797 =
33. 33.589 − 299 =
34. 34.793 − 488 =
35. 35.960 − 649 =
36. 36.183 − 147 =
37. 37.359 − 169 =
38. 38.709 − 369 =
39. 39.721 − 599 =
40. 40.920 − 587 =

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