Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 454 · 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. 1.999 − 499 =
2. 2.716 − 467 =
3. 3.924 − 799 =
4. 4.534 − 459 =
5. 5.803 − 397 =
6. 6.868 − 798 =
7. 7.556 − 537 =
8. 8.874 − 407 =
9. 9.733 − 599 =
10. 10.472 − 258 =
11. 11.977 − 697 =
12. 12.845 − 198 =
13. 13.744 − 669 =
14. 14.363 − 199 =
15. 15.950 − 498 =
16. 16.860 − 797 =
17. 17.511 − 117 =
18. 18.630 − 219 =
19. 19.725 − 689 =
20. 20.793 − 698 =
21. 21.641 − 499 =
22. 22.806 − 699 =
23. 23.464 − 177 =
24. 24.965 − 797 =
25. 25.766 − 499 =
26. 26.766 − 698 =
27. 27.787 − 397 =
28. 28.853 − 197 =
29. 29.971 − 398 =
30. 30.769 − 117 =
31. 31.929 − 198 =
32. 32.982 − 398 =
33. 33.988 − 668 =
34. 34.826 − 649 =
35. 35.877 − 699 =
36. 36.899 − 518 =
37. 37.804 − 299 =
38. 38.741 − 698 =
39. 39.456 − 298 =
40. 40.499 − 397 =

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