Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 230 · 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. 1.837 − 397 =
2. 2.878 − 698 =
3. 3.545 − 498 =
4. 4.810 − 397 =
5. 5.678 − 587 =
6. 6.626 − 398 =
7. 7.706 − 499 =
8. 8.720 − 699 =
9. 9.971 − 557 =
10. 10.946 − 597 =
11. 11.520 − 159 =
12. 12.515 − 379 =
13. 13.282 − 199 =
14. 14.298 − 198 =
15. 15.416 − 389 =
16. 16.815 − 607 =
17. 17.721 − 568 =
18. 18.720 − 599 =
19. 19.760 − 497 =
20. 20.818 − 259 =
21. 21.240 − 207 =
22. 22.939 − 567 =
23. 23.749 − 168 =
24. 24.801 − 319 =
25. 25.488 − 467 =
26. 26.923 − 699 =
27. 27.818 − 587 =
28. 28.960 − 798 =
29. 29.795 − 297 =
30. 30.877 − 599 =
31. 31.837 − 189 =
32. 32.694 − 337 =
33. 33.936 − 198 =
34. 34.350 − 299 =
35. 35.472 − 197 =
36. 36.636 − 429 =
37. 37.910 − 398 =
38. 38.717 − 597 =
39. 39.499 − 277 =
40. 40.825 − 247 =

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