Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 137 · 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. 1.791 − 648 =
2. 2.980 − 398 =
3. 3.558 − 128 =
4. 4.803 − 427 =
5. 5.352 − 298 =
6. 6.885 − 398 =
7. 7.574 − 397 =
8. 8.570 − 519 =
9. 9.963 − 798 =
10. 10.321 − 199 =
11. 11.776 − 198 =
12. 12.847 − 699 =
13. 13.732 − 189 =
14. 14.265 − 158 =
15. 15.708 − 509 =
16. 16.228 − 197 =
17. 17.641 − 147 =
18. 18.656 − 587 =
19. 19.373 − 188 =
20. 20.389 − 219 =
21. 21.734 − 597 =
22. 22.537 − 499 =
23. 23.266 − 187 =
24. 24.471 − 397 =
25. 25.590 − 248 =
26. 26.875 − 798 =
27. 27.968 − 699 =
28. 28.925 − 697 =
29. 29.724 − 297 =
30. 30.668 − 598 =
31. 31.861 − 199 =
32. 32.824 − 127 =
33. 33.660 − 538 =
34. 34.693 − 419 =
35. 35.833 − 687 =
36. 36.611 − 367 =
37. 37.558 − 309 =
38. 38.779 − 597 =
39. 39.937 − 499 =
40. 40.707 − 597 =

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