Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 228 · 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. 1.844 − 499 =
2. 2.531 − 498 =
3. 3.774 − 297 =
4. 4.863 − 468 =
5. 5.989 − 249 =
6. 6.815 − 609 =
7. 7.927 − 269 =
8. 8.852 − 618 =
9. 9.749 − 299 =
10. 10.729 − 399 =
11. 11.737 − 297 =
12. 12.715 − 497 =
13. 13.892 − 658 =
14. 14.800 − 657 =
15. 15.513 − 498 =
16. 16.575 − 497 =
17. 17.778 − 597 =
18. 18.840 − 497 =
19. 19.637 − 398 =
20. 20.689 − 277 =
21. 21.835 − 178 =
22. 22.568 − 469 =
23. 23.544 − 498 =
24. 24.919 − 497 =
25. 25.929 − 628 =
26. 26.392 − 249 =
27. 27.476 − 328 =
28. 28.871 − 538 =
29. 29.363 − 337 =
30. 30.651 − 499 =
31. 31.525 − 497 =
32. 32.354 − 199 =
33. 33.902 − 298 =
34. 34.892 − 399 =
35. 35.961 − 798 =
36. 36.664 − 599 =
37. 37.949 − 447 =
38. 38.801 − 189 =
39. 39.872 − 497 =
40. 40.487 − 298 =

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