Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 401 · 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. 1.582 − 499 =
2. 2.809 − 699 =
3. 3.503 − 217 =
4. 4.785 − 287 =
5. 5.924 − 499 =
6. 6.885 − 598 =
7. 7.923 − 497 =
8. 8.860 − 298 =
9. 9.977 − 337 =
10. 10.448 − 299 =
11. 11.679 − 238 =
12. 12.688 − 199 =
13. 13.691 − 598 =
14. 14.826 − 127 =
15. 15.972 − 798 =
16. 16.778 − 698 =
17. 17.311 − 289 =
18. 18.508 − 198 =
19. 19.755 − 298 =
20. 20.364 − 297 =
21. 21.973 − 797 =
22. 22.905 − 547 =
23. 23.674 − 497 =
24. 24.825 − 798 =
25. 25.951 − 799 =
26. 26.778 − 699 =
27. 27.827 − 599 =
28. 28.539 − 279 =
29. 29.890 − 687 =
30. 30.816 − 798 =
31. 31.992 − 797 =
32. 32.493 − 227 =
33. 33.947 − 699 =
34. 34.817 − 599 =
35. 35.343 − 147 =
36. 36.255 − 198 =
37. 37.475 − 349 =
38. 38.269 − 198 =
39. 39.977 − 498 =
40. 40.556 − 399 =

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