Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 919 · 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. 1.232 − 177 =
2. 2.821 − 597 =
3. 3.620 − 599 =
4. 4.360 − 198 =
5. 5.959 − 797 =
6. 6.799 − 239 =
7. 7.828 − 797 =
8. 8.814 − 198 =
9. 9.464 − 149 =
10. 10.478 − 398 =
11. 11.799 − 657 =
12. 12.529 − 499 =
13. 13.510 − 299 =
14. 14.392 − 229 =
15. 15.945 − 699 =
16. 16.681 − 497 =
17. 17.946 − 627 =
18. 18.165 − 148 =
19. 19.243 − 158 =
20. 20.488 − 198 =
21. 21.743 − 648 =
22. 22.922 − 678 =
23. 23.658 − 498 =
24. 24.439 − 299 =
25. 25.617 − 507 =
26. 26.517 − 498 =
27. 27.801 − 399 =
28. 28.358 − 197 =
29. 29.990 − 299 =
30. 30.751 − 699 =
31. 31.698 − 647 =
32. 32.794 − 198 =
33. 33.602 − 398 =
34. 34.797 − 668 =
35. 35.438 − 368 =
36. 36.673 − 299 =
37. 37.295 − 189 =
38. 38.956 − 598 =
39. 39.784 − 268 =
40. 40.340 − 197 =

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