Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 47 · 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. 1.906 − 398 =
2. 2.789 − 268 =
3. 3.969 − 798 =
4. 4.948 − 638 =
5. 5.690 − 149 =
6. 6.680 − 658 =
7. 7.714 − 549 =
8. 8.522 − 397 =
9. 9.612 − 547 =
10. 10.782 − 698 =
11. 11.982 − 297 =
12. 12.681 − 567 =
13. 13.931 − 539 =
14. 14.703 − 497 =
15. 15.430 − 397 =
16. 16.429 − 298 =
17. 17.841 − 168 =
18. 18.790 − 219 =
19. 19.683 − 338 =
20. 20.641 − 297 =
21. 21.768 − 697 =
22. 22.814 − 799 =
23. 23.859 − 668 =
24. 24.701 − 139 =
25. 25.658 − 158 =
26. 26.728 − 298 =
27. 27.999 − 518 =
28. 28.944 − 567 =
29. 29.510 − 389 =
30. 30.375 − 207 =
31. 31.764 − 499 =
32. 32.315 − 148 =
33. 33.529 − 248 =
34. 34.474 − 398 =
35. 35.943 − 497 =
36. 36.988 − 118 =
37. 37.934 − 798 =
38. 38.673 − 598 =
39. 39.657 − 437 =
40. 40.362 − 299 =

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