Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 690 · 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. 1.765 − 227 =
2. 2.586 − 417 =
3. 3.968 − 198 =
4. 4.372 − 199 =
5. 5.665 − 497 =
6. 6.970 − 499 =
7. 7.252 − 129 =
8. 8.725 − 497 =
9. 9.898 − 469 =
10. 10.880 − 677 =
11. 11.995 − 698 =
12. 12.819 − 238 =
13. 13.982 − 637 =
14. 14.710 − 599 =
15. 15.670 − 548 =
16. 16.694 − 599 =
17. 17.882 − 407 =
18. 18.733 − 297 =
19. 19.692 − 598 =
20. 20.376 − 199 =
21. 21.937 − 597 =
22. 22.746 − 397 =
23. 23.934 − 568 =
24. 24.668 − 209 =
25. 25.892 − 499 =
26. 26.968 − 697 =
27. 27.940 − 297 =
28. 28.999 − 497 =
29. 29.179 − 118 =
30. 30.838 − 699 =
31. 31.252 − 198 =
32. 32.747 − 399 =
33. 33.547 − 197 =
34. 34.777 − 398 =
35. 35.717 − 699 =
36. 36.782 − 598 =
37. 37.797 − 689 =
38. 38.530 − 417 =
39. 39.909 − 398 =
40. 40.980 − 319 =

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