Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 524 · 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. 1.837 − 797 =
2. 2.398 − 198 =
3. 3.980 − 597 =
4. 4.907 − 609 =
5. 5.283 − 199 =
6. 6.945 − 659 =
7. 7.844 − 799 =
8. 8.607 − 199 =
9. 9.921 − 669 =
10. 10.875 − 598 =
11. 11.906 − 699 =
12. 12.940 − 548 =
13. 13.428 − 397 =
14. 14.823 − 799 =
15. 15.639 − 597 =
16. 16.949 − 797 =
17. 17.852 − 619 =
18. 18.533 − 499 =
19. 19.845 − 338 =
20. 20.804 − 398 =
21. 21.971 − 558 =
22. 22.852 − 598 =
23. 23.553 − 198 =
24. 24.726 − 498 =
25. 25.910 − 699 =
26. 26.784 − 517 =
27. 27.748 − 399 =
28. 28.923 − 427 =
29. 29.840 − 799 =
30. 30.902 − 197 =
31. 31.535 − 299 =
32. 32.484 − 449 =
33. 33.456 − 319 =
34. 34.928 − 697 =
35. 35.786 − 599 =
36. 36.984 − 537 =
37. 37.997 − 398 =
38. 38.858 − 698 =
39. 39.670 − 478 =
40. 40.559 − 398 =

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