Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 838 · 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. 1.337 − 127 =
2. 2.866 − 599 =
3. 3.498 − 298 =
4. 4.993 − 198 =
5. 5.866 − 797 =
6. 6.978 − 308 =
7. 7.631 − 599 =
8. 8.941 − 399 =
9. 9.356 − 299 =
10. 10.951 − 697 =
11. 11.635 − 548 =
12. 12.842 − 618 =
13. 13.869 − 697 =
14. 14.882 − 458 =
15. 15.773 − 678 =
16. 16.541 − 449 =
17. 17.852 − 359 =
18. 18.511 − 288 =
19. 19.830 − 399 =
20. 20.812 − 698 =
21. 21.726 − 699 =
22. 22.997 − 299 =
23. 23.401 − 197 =
24. 24.546 − 267 =
25. 25.808 − 699 =
26. 26.236 − 197 =
27. 27.670 − 299 =
28. 28.546 − 297 =
29. 29.946 − 697 =
30. 30.919 − 559 =
31. 31.635 − 399 =
32. 32.791 − 377 =
33. 33.999 − 398 =
34. 34.998 − 797 =
35. 35.543 − 498 =
36. 36.973 − 319 =
37. 37.779 − 467 =
38. 38.893 − 799 =
39. 39.519 − 139 =
40. 40.704 − 387 =

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