Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 670 · 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. 1.678 − 497 =
2. 2.461 − 297 =
3. 3.928 − 797 =
4. 4.937 − 629 =
5. 5.810 − 598 =
6. 6.772 − 637 =
7. 7.962 − 308 =
8. 8.672 − 467 =
9. 9.508 − 137 =
10. 10.627 − 289 =
11. 11.290 − 208 =
12. 12.377 − 329 =
13. 13.959 − 399 =
14. 14.670 − 518 =
15. 15.953 − 199 =
16. 16.456 − 299 =
17. 17.715 − 299 =
18. 18.868 − 488 =
19. 19.832 − 699 =
20. 20.939 − 497 =
21. 21.648 − 598 =
22. 22.848 − 599 =
23. 23.501 − 199 =
24. 24.880 − 797 =
25. 25.819 − 399 =
26. 26.756 − 698 =
27. 27.878 − 698 =
28. 28.735 − 599 =
29. 29.916 − 399 =
30. 30.326 − 299 =
31. 31.733 − 598 =
32. 32.918 − 799 =
33. 33.848 − 197 =
34. 34.992 − 179 =
35. 35.763 − 198 =
36. 36.782 − 188 =
37. 37.822 − 498 =
38. 38.797 − 699 =
39. 39.890 − 797 =
40. 40.583 − 399 =

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