Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 244 · 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. 1.229 − 197 =
2. 2.972 − 398 =
3. 3.795 − 538 =
4. 4.479 − 299 =
5. 5.379 − 198 =
6. 6.630 − 599 =
7. 7.613 − 399 =
8. 8.786 − 449 =
9. 9.711 − 499 =
10. 10.665 − 139 =
11. 11.896 − 698 =
12. 12.702 − 649 =
13. 13.695 − 298 =
14. 14.363 − 277 =
15. 15.822 − 597 =
16. 16.730 − 497 =
17. 17.925 − 299 =
18. 18.712 − 499 =
19. 19.808 − 198 =
20. 20.643 − 497 =
21. 21.581 − 527 =
22. 22.806 − 619 =
23. 23.869 − 509 =
24. 24.827 − 799 =
25. 25.690 − 507 =
26. 26.918 − 457 =
27. 27.930 − 798 =
28. 28.368 − 147 =
29. 29.620 − 398 =
30. 30.581 − 498 =
31. 31.532 − 299 =
32. 32.962 − 498 =
33. 33.780 − 379 =
34. 34.869 − 597 =
35. 35.952 − 797 =
36. 36.329 − 299 =
37. 37.463 − 297 =
38. 38.856 − 697 =
39. 39.975 − 278 =
40. 40.892 − 497 =

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