Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 496 · 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. 1.806 − 398 =
2. 2.809 − 358 =
3. 3.979 − 498 =
4. 4.707 − 529 =
5. 5.751 − 298 =
6. 6.727 − 159 =
7. 7.820 − 798 =
8. 8.995 − 699 =
9. 9.812 − 698 =
10. 10.860 − 397 =
11. 11.743 − 409 =
12. 12.969 − 697 =
13. 13.348 − 197 =
14. 14.973 − 638 =
15. 15.747 − 499 =
16. 16.988 − 489 =
17. 17.997 − 487 =
18. 18.971 − 397 =
19. 19.782 − 688 =
20. 20.983 − 497 =
21. 21.867 − 497 =
22. 22.946 − 569 =
23. 23.784 − 698 =
24. 24.222 − 199 =
25. 25.976 − 599 =
26. 26.346 − 247 =
27. 27.491 − 399 =
28. 28.927 − 697 =
29. 29.231 − 199 =
30. 30.967 − 799 =
31. 31.851 − 498 =
32. 32.877 − 299 =
33. 33.927 − 649 =
34. 34.447 − 298 =
35. 35.627 − 609 =
36. 36.882 − 627 =
37. 37.875 − 498 =
38. 38.531 − 197 =
39. 39.765 − 337 =
40. 40.793 − 687 =

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