Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 940 · 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. 1.888 − 329 =
2. 2.928 − 168 =
3. 3.620 − 537 =
4. 4.775 − 257 =
5. 5.916 − 798 =
6. 6.302 − 159 =
7. 7.812 − 699 =
8. 8.785 − 598 =
9. 9.945 − 197 =
10. 10.373 − 299 =
11. 11.937 − 657 =
12. 12.841 − 498 =
13. 13.635 − 297 =
14. 14.949 − 218 =
15. 15.907 − 797 =
16. 16.984 − 699 =
17. 17.909 − 499 =
18. 18.835 − 357 =
19. 19.767 − 698 =
20. 20.524 − 459 =
21. 21.448 − 299 =
22. 22.976 − 599 =
23. 23.681 − 297 =
24. 24.630 − 297 =
25. 25.694 − 499 =
26. 26.948 − 389 =
27. 27.935 − 409 =
28. 28.613 − 398 =
29. 29.842 − 698 =
30. 30.474 − 367 =
31. 31.651 − 297 =
32. 32.766 − 617 =
33. 33.693 − 139 =
34. 34.502 − 387 =
35. 35.801 − 509 =
36. 36.463 − 319 =
37. 37.772 − 478 =
38. 38.418 − 397 =
39. 39.748 − 598 =
40. 40.782 − 498 =

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