Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 769 · 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. 1.627 − 599 =
2. 2.831 − 688 =
3. 3.680 − 628 =
4. 4.342 − 229 =
5. 5.947 − 699 =
6. 6.689 − 398 =
7. 7.813 − 799 =
8. 8.924 − 798 =
9. 9.852 − 339 =
10. 10.820 − 798 =
11. 11.401 − 198 =
12. 12.802 − 698 =
13. 13.518 − 498 =
14. 14.741 − 599 =
15. 15.885 − 597 =
16. 16.685 − 299 =
17. 17.821 − 537 =
18. 18.723 − 597 =
19. 19.928 − 129 =
20. 20.370 − 198 =
21. 21.701 − 199 =
22. 22.894 − 407 =
23. 23.530 − 448 =
24. 24.345 − 119 =
25. 25.762 − 697 =
26. 26.729 − 348 =
27. 27.861 − 799 =
28. 28.852 − 239 =
29. 29.873 − 137 =
30. 30.996 − 599 =
31. 31.307 − 207 =
32. 32.902 − 698 =
33. 33.383 − 218 =
34. 34.329 − 309 =
35. 35.953 − 598 =
36. 36.451 − 118 =
37. 37.720 − 298 =
38. 38.760 − 599 =
39. 39.921 − 597 =
40. 40.172 − 159 =

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