Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 836 · 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. 1.855 − 697 =
2. 2.758 − 278 =
3. 3.852 − 597 =
4. 4.583 − 298 =
5. 5.806 − 599 =
6. 6.976 − 699 =
7. 7.867 − 697 =
8. 8.895 − 197 =
9. 9.745 − 397 =
10. 10.866 − 297 =
11. 11.955 − 297 =
12. 12.802 − 699 =
13. 13.989 − 699 =
14. 14.430 − 197 =
15. 15.631 − 517 =
16. 16.998 − 669 =
17. 17.722 − 697 =
18. 18.511 − 397 =
19. 19.711 − 519 =
20. 20.782 − 698 =
21. 21.892 − 558 =
22. 22.592 − 499 =
23. 23.442 − 419 =
24. 24.935 − 198 =
25. 25.866 − 599 =
26. 26.932 − 598 =
27. 27.660 − 297 =
28. 28.871 − 199 =
29. 29.982 − 599 =
30. 30.576 − 499 =
31. 31.722 − 489 =
32. 32.458 − 198 =
33. 33.832 − 797 =
34. 34.675 − 197 =
35. 35.980 − 538 =
36. 36.907 − 798 =
37. 37.584 − 297 =
38. 38.755 − 598 =
39. 39.638 − 597 =
40. 40.573 − 198 =

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