Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 538 · 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. 1.861 − 687 =
2. 2.953 − 799 =
3. 3.979 − 697 =
4. 4.926 − 348 =
5. 5.879 − 467 =
6. 6.711 − 497 =
7. 7.892 − 297 =
8. 8.838 − 199 =
9. 9.896 − 238 =
10. 10.569 − 297 =
11. 11.998 − 697 =
12. 12.778 − 418 =
13. 13.741 − 498 =
14. 14.717 − 588 =
15. 15.995 − 549 =
16. 16.854 − 797 =
17. 17.798 − 597 =
18. 18.737 − 628 =
19. 19.841 − 499 =
20. 20.423 − 278 =
21. 21.916 − 379 =
22. 22.909 − 499 =
23. 23.955 − 419 =
24. 24.684 − 199 =
25. 25.962 − 797 =
26. 26.843 − 798 =
27. 27.936 − 459 =
28. 28.375 − 297 =
29. 29.779 − 689 =
30. 30.650 − 498 =
31. 31.801 − 509 =
32. 32.788 − 589 =
33. 33.957 − 797 =
34. 34.554 − 197 =
35. 35.741 − 547 =
36. 36.950 − 548 =
37. 37.804 − 597 =
38. 38.929 − 799 =
39. 39.752 − 237 =
40. 40.600 − 498 =

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