Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 704 · 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. 1.808 − 159 =
2. 2.601 − 507 =
3. 3.353 − 269 =
4. 4.819 − 598 =
5. 5.735 − 399 =
6. 6.784 − 279 =
7. 7.789 − 518 =
8. 8.809 − 698 =
9. 9.838 − 368 =
10. 10.948 − 198 =
11. 11.778 − 699 =
12. 12.514 − 187 =
13. 13.682 − 307 =
14. 14.611 − 507 =
15. 15.967 − 699 =
16. 16.976 − 499 =
17. 17.800 − 429 =
18. 18.991 − 519 =
19. 19.749 − 699 =
20. 20.247 − 199 =
21. 21.758 − 299 =
22. 22.276 − 227 =
23. 23.823 − 697 =
24. 24.928 − 558 =
25. 25.896 − 798 =
26. 26.721 − 568 =
27. 27.786 − 138 =
28. 28.937 − 419 =
29. 29.516 − 328 =
30. 30.752 − 599 =
31. 31.501 − 297 =
32. 32.479 − 139 =
33. 33.764 − 448 =
34. 34.579 − 209 =
35. 35.685 − 299 =
36. 36.846 − 697 =
37. 37.953 − 397 =
38. 38.869 − 139 =
39. 39.741 − 499 =
40. 40.618 − 339 =

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