Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 680 · 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. 1.896 − 798 =
2. 2.540 − 507 =
3. 3.210 − 138 =
4. 4.539 − 199 =
5. 5.235 − 199 =
6. 6.635 − 499 =
7. 7.892 − 799 =
8. 8.788 − 349 =
9. 9.879 − 499 =
10. 10.385 − 298 =
11. 11.915 − 297 =
12. 12.454 − 229 =
13. 13.891 − 679 =
14. 14.770 − 598 =
15. 15.492 − 398 =
16. 16.972 − 797 =
17. 17.615 − 367 =
18. 18.766 − 697 =
19. 19.729 − 598 =
20. 20.685 − 399 =
21. 21.979 − 398 =
22. 22.737 − 448 =
23. 23.806 − 298 =
24. 24.975 − 498 =
25. 25.268 − 228 =
26. 26.839 − 797 =
27. 27.641 − 557 =
28. 28.592 − 498 =
29. 29.585 − 558 =
30. 30.794 − 579 =
31. 31.656 − 399 =
32. 32.949 − 559 =
33. 33.310 − 198 =
34. 34.915 − 798 =
35. 35.787 − 599 =
36. 36.822 − 647 =
37. 37.948 − 679 =
38. 38.532 − 497 =
39. 39.463 − 348 =
40. 40.649 − 139 =

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