Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 714 · 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. 1.418 − 298 =
2. 2.918 − 458 =
3. 3.424 − 409 =
4. 4.753 − 699 =
5. 5.791 − 597 =
6. 6.850 − 597 =
7. 7.741 − 699 =
8. 8.752 − 438 =
9. 9.625 − 268 =
10. 10.981 − 198 =
11. 11.548 − 118 =
12. 12.919 − 339 =
13. 13.799 − 597 =
14. 14.700 − 447 =
15. 15.717 − 688 =
16. 16.898 − 498 =
17. 17.749 − 689 =
18. 18.495 − 328 =
19. 19.481 − 297 =
20. 20.942 − 598 =
21. 21.286 − 118 =
22. 22.999 − 798 =
23. 23.967 − 339 =
24. 24.460 − 369 =
25. 25.377 − 167 =
26. 26.804 − 399 =
27. 27.859 − 697 =
28. 28.611 − 398 =
29. 29.610 − 489 =
30. 30.470 − 397 =
31. 31.719 − 599 =
32. 32.433 − 238 =
33. 33.899 − 269 =
34. 34.408 − 197 =
35. 35.706 − 499 =
36. 36.668 − 517 =
37. 37.856 − 699 =
38. 38.968 − 159 =
39. 39.935 − 799 =
40. 40.501 − 299 =

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