Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 615 · 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. 1.849 − 799 =
2. 2.773 − 417 =
3. 3.607 − 588 =
4. 4.922 − 457 =
5. 5.790 − 537 =
6. 6.372 − 297 =
7. 7.661 − 199 =
8. 8.918 − 258 =
9. 9.993 − 697 =
10. 10.266 − 199 =
11. 11.537 − 498 =
12. 12.719 − 697 =
13. 13.645 − 567 =
14. 14.520 − 179 =
15. 15.994 − 397 =
16. 16.850 − 247 =
17. 17.980 − 198 =
18. 18.382 − 299 =
19. 19.657 − 299 =
20. 20.801 − 699 =
21. 21.849 − 298 =
22. 22.950 − 197 =
23. 23.497 − 299 =
24. 24.958 − 377 =
25. 25.499 − 397 =
26. 26.868 − 399 =
27. 27.873 − 199 =
28. 28.563 − 449 =
29. 29.993 − 797 =
30. 30.937 − 549 =
31. 31.791 − 477 =
32. 32.877 − 499 =
33. 33.470 − 388 =
34. 34.961 − 699 =
35. 35.984 − 699 =
36. 36.665 − 517 =
37. 37.687 − 298 =
38. 38.954 − 498 =
39. 39.745 − 197 =
40. 40.934 − 197 =

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