Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 605 · 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. 1.833 − 478 =
2. 2.816 − 549 =
3. 3.818 − 408 =
4. 4.641 − 428 =
5. 5.923 − 298 =
6. 6.972 − 697 =
7. 7.585 − 497 =
8. 8.832 − 799 =
9. 9.863 − 489 =
10. 10.460 − 219 =
11. 11.784 − 698 =
12. 12.997 − 489 =
13. 13.826 − 198 =
14. 14.821 − 699 =
15. 15.240 − 139 =
16. 16.878 − 199 =
17. 17.975 − 599 =
18. 18.922 − 697 =
19. 19.596 − 537 =
20. 20.960 − 798 =
21. 21.632 − 507 =
22. 22.648 − 498 =
23. 23.633 − 498 =
24. 24.856 − 297 =
25. 25.683 − 399 =
26. 26.835 − 559 =
27. 27.846 − 598 =
28. 28.931 − 237 =
29. 29.799 − 389 =
30. 30.624 − 438 =
31. 31.898 − 797 =
32. 32.583 − 339 =
33. 33.560 − 399 =
34. 34.730 − 699 =
35. 35.878 − 799 =
36. 36.823 − 798 =
37. 37.753 − 557 =
38. 38.886 − 507 =
39. 39.879 − 699 =
40. 40.576 − 297 =

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