Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 787 · 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. 1.923 − 799 =
2. 2.823 − 498 =
3. 3.634 − 398 =
4. 4.734 − 599 =
5. 5.460 − 298 =
6. 6.406 − 199 =
7. 7.958 − 158 =
8. 8.851 − 698 =
9. 9.838 − 647 =
10. 10.914 − 669 =
11. 11.844 − 399 =
12. 12.940 − 799 =
13. 13.623 − 498 =
14. 14.697 − 598 =
15. 15.968 − 699 =
16. 16.846 − 699 =
17. 17.786 − 218 =
18. 18.973 − 637 =
19. 19.931 − 527 =
20. 20.451 − 397 =
21. 21.224 − 199 =
22. 22.807 − 399 =
23. 23.852 − 499 =
24. 24.464 − 197 =
25. 25.574 − 259 =
26. 26.730 − 198 =
27. 27.885 − 499 =
28. 28.737 − 497 =
29. 29.550 − 429 =
30. 30.891 − 437 =
31. 31.998 − 357 =
32. 32.718 − 299 =
33. 33.325 − 169 =
34. 34.462 − 357 =
35. 35.998 − 797 =
36. 36.864 − 799 =
37. 37.602 − 199 =
38. 38.644 − 607 =
39. 39.456 − 197 =
40. 40.719 − 197 =

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