Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 887 · 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. 1.881 − 148 =
2. 2.843 − 798 =
3. 3.607 − 497 =
4. 4.672 − 147 =
5. 5.793 − 577 =
6. 6.850 − 527 =
7. 7.612 − 497 =
8. 8.956 − 287 =
9. 9.394 − 318 =
10. 10.959 − 798 =
11. 11.749 − 397 =
12. 12.863 − 167 =
13. 13.853 − 697 =
14. 14.994 − 398 =
15. 15.973 − 409 =
16. 16.576 − 499 =
17. 17.468 − 338 =
18. 18.797 − 689 =
19. 19.804 − 197 =
20. 20.799 − 429 =
21. 21.540 − 199 =
22. 22.713 − 199 =
23. 23.955 − 698 =
24. 24.394 − 378 =
25. 25.844 − 489 =
26. 26.805 − 599 =
27. 27.572 − 498 =
28. 28.831 − 179 =
29. 29.729 − 157 =
30. 30.342 − 178 =
31. 31.474 − 319 =
32. 32.893 − 659 =
33. 33.840 − 798 =
34. 34.333 − 198 =
35. 35.627 − 299 =
36. 36.935 − 247 =
37. 37.740 − 398 =
38. 38.792 − 658 =
39. 39.656 − 199 =
40. 40.662 − 478 =

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