Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 938 · 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. 1.765 − 488 =
2. 2.990 − 357 =
3. 3.472 − 247 =
4. 4.834 − 608 =
5. 5.881 − 129 =
6. 6.390 − 258 =
7. 7.870 − 287 =
8. 8.807 − 198 =
9. 9.412 − 288 =
10. 10.610 − 198 =
11. 11.983 − 559 =
12. 12.897 − 799 =
13. 13.768 − 298 =
14. 14.852 − 479 =
15. 15.311 − 219 =
16. 16.845 − 299 =
17. 17.437 − 399 =
18. 18.899 − 498 =
19. 19.784 − 498 =
20. 20.712 − 579 =
21. 21.503 − 228 =
22. 22.450 − 219 =
23. 23.676 − 519 =
24. 24.867 − 699 =
25. 25.812 − 799 =
26. 26.866 − 798 =
27. 27.888 − 798 =
28. 28.765 − 698 =
29. 29.522 − 499 =
30. 30.440 − 198 =
31. 31.526 − 399 =
32. 32.836 − 599 =
33. 33.652 − 497 =
34. 34.972 − 649 =
35. 35.882 − 797 =
36. 36.863 − 358 =
37. 37.699 − 557 =
38. 38.531 − 498 =
39. 39.405 − 139 =
40. 40.685 − 597 =

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