Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 415 · 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. 1.567 − 279 =
2. 2.755 − 607 =
3. 3.685 − 498 =
4. 4.776 − 698 =
5. 5.976 − 337 =
6. 6.774 − 599 =
7. 7.824 − 698 =
8. 8.951 − 299 =
9. 9.796 − 627 =
10. 10.470 − 198 =
11. 11.548 − 367 =
12. 12.975 − 398 =
13. 13.505 − 199 =
14. 14.533 − 297 =
15. 15.756 − 629 =
16. 16.861 − 797 =
17. 17.627 − 399 =
18. 18.888 − 498 =
19. 19.386 − 197 =
20. 20.792 − 199 =
21. 21.963 − 447 =
22. 22.347 − 198 =
23. 23.696 − 598 =
24. 24.986 − 199 =
25. 25.617 − 207 =
26. 26.793 − 699 =
27. 27.815 − 697 =
28. 28.755 − 297 =
29. 29.947 − 397 =
30. 30.948 − 668 =
31. 31.225 − 197 =
32. 32.887 − 597 =
33. 33.281 − 199 =
34. 34.347 − 199 =
35. 35.912 − 799 =
36. 36.777 − 307 =
37. 37.447 − 198 =
38. 38.989 − 299 =
39. 39.934 − 297 =
40. 40.413 − 188 =

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