Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 188 · 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. 1.690 − 497 =
2. 2.273 − 199 =
3. 3.758 − 398 =
4. 4.783 − 137 =
5. 5.295 − 197 =
6. 6.721 − 529 =
7. 7.539 − 368 =
8. 8.541 − 499 =
9. 9.567 − 199 =
10. 10.629 − 298 =
11. 11.436 − 398 =
12. 12.647 − 207 =
13. 13.954 − 798 =
14. 14.936 − 327 =
15. 15.445 − 279 =
16. 16.724 − 699 =
17. 17.906 − 798 =
18. 18.776 − 297 =
19. 19.736 − 308 =
20. 20.745 − 597 =
21. 21.436 − 258 =
22. 22.884 − 698 =
23. 23.653 − 579 =
24. 24.848 − 258 =
25. 25.671 − 498 =
26. 26.833 − 599 =
27. 27.821 − 397 =
28. 28.573 − 499 =
29. 29.849 − 797 =
30. 30.570 − 497 =
31. 31.850 − 598 =
32. 32.966 − 298 =
33. 33.645 − 498 =
34. 34.536 − 288 =
35. 35.834 − 599 =
36. 36.941 − 529 =
37. 37.566 − 158 =
38. 38.887 − 598 =
39. 39.488 − 198 =
40. 40.960 − 499 =

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