Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 783 · 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. 1.912 − 608 =
2. 2.449 − 298 =
3. 3.783 − 597 =
4. 4.847 − 798 =
5. 5.895 − 797 =
6. 6.976 − 797 =
7. 7.808 − 697 =
8. 8.764 − 198 =
9. 9.518 − 249 =
10. 10.644 − 517 =
11. 11.377 − 229 =
12. 12.821 − 797 =
13. 13.787 − 277 =
14. 14.541 − 518 =
15. 15.311 − 237 =
16. 16.726 − 197 =
17. 17.334 − 218 =
18. 18.553 − 229 =
19. 19.467 − 168 =
20. 20.738 − 697 =
21. 21.786 − 697 =
22. 22.778 − 509 =
23. 23.873 − 297 =
24. 24.814 − 398 =
25. 25.990 − 689 =
26. 26.943 − 628 =
27. 27.945 − 419 =
28. 28.245 − 147 =
29. 29.873 − 137 =
30. 30.989 − 297 =
31. 31.991 − 657 =
32. 32.699 − 498 =
33. 33.655 − 197 =
34. 34.638 − 599 =
35. 35.885 − 618 =
36. 36.596 − 568 =
37. 37.691 − 397 =
38. 38.931 − 448 =
39. 39.781 − 697 =
40. 40.735 − 637 =

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