Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 139 · 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. 1.720 − 699 =
2. 2.955 − 658 =
3. 3.972 − 547 =
4. 4.728 − 497 =
5. 5.956 − 699 =
6. 6.583 − 388 =
7. 7.500 − 297 =
8. 8.782 − 388 =
9. 9.924 − 798 =
10. 10.430 − 199 =
11. 11.751 − 598 =
12. 12.480 − 199 =
13. 13.851 − 507 =
14. 14.987 − 798 =
15. 15.862 − 697 =
16. 16.868 − 348 =
17. 17.405 − 298 =
18. 18.891 − 797 =
19. 19.973 − 799 =
20. 20.999 − 627 =
21. 21.993 − 527 =
22. 22.585 − 297 =
23. 23.842 − 499 =
24. 24.576 − 527 =
25. 25.629 − 337 =
26. 26.823 − 169 =
27. 27.839 − 699 =
28. 28.996 − 297 =
29. 29.711 − 199 =
30. 30.350 − 167 =
31. 31.947 − 599 =
32. 32.927 − 798 =
33. 33.778 − 699 =
34. 34.523 − 117 =
35. 35.806 − 368 =
36. 36.634 − 397 =
37. 37.647 − 257 =
38. 38.730 − 139 =
39. 39.956 − 798 =
40. 40.965 − 287 =

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