Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 804 · 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. 1.789 − 397 =
2. 2.623 − 299 =
3. 3.550 − 459 =
4. 4.702 − 609 =
5. 5.690 − 597 =
6. 6.458 − 198 =
7. 7.514 − 418 =
8. 8.879 − 297 =
9. 9.949 − 649 =
10. 10.546 − 497 =
11. 11.754 − 397 =
12. 12.856 − 569 =
13. 13.921 − 599 =
14. 14.826 − 399 =
15. 15.675 − 298 =
16. 16.700 − 598 =
17. 17.538 − 478 =
18. 18.700 − 397 =
19. 19.674 − 539 =
20. 20.873 − 799 =
21. 21.636 − 588 =
22. 22.945 − 597 =
23. 23.251 − 127 =
24. 24.599 − 388 =
25. 25.821 − 697 =
26. 26.824 − 699 =
27. 27.973 − 799 =
28. 28.501 − 229 =
29. 29.685 − 568 =
30. 30.867 − 799 =
31. 31.775 − 699 =
32. 32.483 − 297 =
33. 33.954 − 118 =
34. 34.527 − 289 =
35. 35.292 − 197 =
36. 36.994 − 797 =
37. 37.899 − 599 =
38. 38.894 − 608 =
39. 39.799 − 298 =
40. 40.763 − 669 =

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