Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 329 · 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. 1.236 − 198 =
2. 2.922 − 257 =
3. 3.510 − 329 =
4. 4.713 − 148 =
5. 5.978 − 598 =
6. 6.923 − 599 =
7. 7.854 − 597 =
8. 8.885 − 797 =
9. 9.715 − 628 =
10. 10.506 − 299 =
11. 11.879 − 197 =
12. 12.787 − 498 =
13. 13.432 − 118 =
14. 14.918 − 429 =
15. 15.564 − 398 =
16. 16.674 − 289 =
17. 17.883 − 699 =
18. 18.826 − 357 =
19. 19.798 − 507 =
20. 20.482 − 298 =
21. 21.792 − 469 =
22. 22.813 − 319 =
23. 23.869 − 599 =
24. 24.786 − 699 =
25. 25.400 − 199 =
26. 26.670 − 599 =
27. 27.727 − 198 =
28. 28.376 − 279 =
29. 29.921 − 499 =
30. 30.464 − 359 =
31. 31.923 − 209 =
32. 32.595 − 317 =
33. 33.732 − 599 =
34. 34.331 − 297 =
35. 35.684 − 398 =
36. 36.884 − 619 =
37. 37.933 − 697 =
38. 38.945 − 298 =
39. 39.508 − 307 =
40. 40.927 − 597 =

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