Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 215 · 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. 1.522 − 497 =
2. 2.947 − 799 =
3. 3.826 − 289 =
4. 4.745 − 648 =
5. 5.643 − 618 =
6. 6.789 − 399 =
7. 7.381 − 179 =
8. 8.660 − 357 =
9. 9.811 − 518 =
10. 10.601 − 578 =
11. 11.736 − 698 =
12. 12.463 − 197 =
13. 13.432 − 357 =
14. 14.273 − 127 =
15. 15.924 − 559 =
16. 16.851 − 458 =
17. 17.786 − 699 =
18. 18.610 − 199 =
19. 19.738 − 697 =
20. 20.854 − 298 =
21. 21.630 − 397 =
22. 22.660 − 289 =
23. 23.722 − 298 =
24. 24.843 − 198 =
25. 25.635 − 569 =
26. 26.648 − 599 =
27. 27.636 − 199 =
28. 28.647 − 158 =
29. 29.890 − 629 =
30. 30.806 − 488 =
31. 31.905 − 678 =
32. 32.811 − 698 =
33. 33.946 − 678 =
34. 34.674 − 449 =
35. 35.923 − 219 =
36. 36.964 − 697 =
37. 37.441 − 268 =
38. 38.802 − 198 =
39. 39.662 − 597 =
40. 40.825 − 679 =

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