Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 678 · 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. 1.495 − 158 =
2. 2.855 − 798 =
3. 3.932 − 697 =
4. 4.724 − 398 =
5. 5.436 − 398 =
6. 6.968 − 697 =
7. 7.776 − 298 =
8. 8.937 − 399 =
9. 9.792 − 189 =
10. 10.804 − 497 =
11. 11.408 − 198 =
12. 12.223 − 198 =
13. 13.346 − 187 =
14. 14.969 − 397 =
15. 15.818 − 248 =
16. 16.411 − 197 =
17. 17.912 − 797 =
18. 18.935 − 598 =
19. 19.716 − 597 =
20. 20.756 − 199 =
21. 21.860 − 179 =
22. 22.405 − 197 =
23. 23.668 − 198 =
24. 24.789 − 199 =
25. 25.792 − 599 =
26. 26.886 − 699 =
27. 27.755 − 399 =
28. 28.647 − 129 =
29. 29.599 − 499 =
30. 30.875 − 497 =
31. 31.432 − 277 =
32. 32.784 − 299 =
33. 33.677 − 597 =
34. 34.930 − 377 =
35. 35.673 − 557 =
36. 36.625 − 457 =
37. 37.980 − 507 =
38. 38.775 − 598 =
39. 39.555 − 498 =
40. 40.842 − 799 =

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