Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 669 · 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 − 597 =
2. 2.788 − 247 =
3. 3.888 − 659 =
4. 4.763 − 577 =
5. 5.713 − 449 =
6. 6.240 − 187 =
7. 7.717 − 667 =
8. 8.482 − 297 =
9. 9.935 − 699 =
10. 10.773 − 277 =
11. 11.497 − 179 =
12. 12.977 − 199 =
13. 13.855 − 198 =
14. 14.764 − 397 =
15. 15.910 − 497 =
16. 16.548 − 169 =
17. 17.756 − 399 =
18. 18.989 − 798 =
19. 19.767 − 679 =
20. 20.618 − 547 =
21. 21.918 − 588 =
22. 22.525 − 388 =
23. 23.424 − 209 =
24. 24.531 − 498 =
25. 25.820 − 699 =
26. 26.840 − 599 =
27. 27.181 − 159 =
28. 28.937 − 679 =
29. 29.505 − 258 =
30. 30.956 − 228 =
31. 31.938 − 397 =
32. 32.891 − 499 =
33. 33.495 − 298 =
34. 34.866 − 498 =
35. 35.987 − 579 =
36. 36.622 − 397 =
37. 37.791 − 499 =
38. 38.957 − 329 =
39. 39.353 − 197 =
40. 40.938 − 597 =

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