Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 918 · 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. 1.810 − 577 =
2. 2.585 − 399 =
3. 3.876 − 677 =
4. 4.705 − 498 =
5. 5.594 − 168 =
6. 6.942 − 399 =
7. 7.527 − 187 =
8. 8.714 − 277 =
9. 9.248 − 198 =
10. 10.647 − 608 =
11. 11.777 − 409 =
12. 12.398 − 337 =
13. 13.920 − 329 =
14. 14.718 − 638 =
15. 15.274 − 177 =
16. 16.608 − 188 =
17. 17.748 − 199 =
18. 18.880 − 798 =
19. 19.520 − 188 =
20. 20.931 − 297 =
21. 21.810 − 397 =
22. 22.896 − 197 =
23. 23.472 − 358 =
24. 24.796 − 228 =
25. 25.633 − 128 =
26. 26.948 − 699 =
27. 27.840 − 198 =
28. 28.782 − 568 =
29. 29.762 − 398 =
30. 30.916 − 579 =
31. 31.702 − 297 =
32. 32.835 − 798 =
33. 33.194 − 179 =
34. 34.825 − 597 =
35. 35.689 − 439 =
36. 36.782 − 668 =
37. 37.904 − 698 =
38. 38.718 − 689 =
39. 39.847 − 599 =
40. 40.851 − 699 =

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