Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 635 · 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. 1.844 − 209 =
2. 2.321 − 299 =
3. 3.432 − 287 =
4. 4.853 − 598 =
5. 5.877 − 497 =
6. 6.829 − 298 =
7. 7.990 − 597 =
8. 8.693 − 678 =
9. 9.911 − 408 =
10. 10.629 − 299 =
11. 11.864 − 597 =
12. 12.876 − 599 =
13. 13.901 − 398 =
14. 14.886 − 538 =
15. 15.363 − 197 =
16. 16.526 − 299 =
17. 17.637 − 397 =
18. 18.398 − 297 =
19. 19.440 − 117 =
20. 20.922 − 698 =
21. 21.959 − 699 =
22. 22.632 − 598 =
23. 23.942 − 548 =
24. 24.924 − 129 =
25. 25.325 − 297 =
26. 26.652 − 447 =
27. 27.664 − 499 =
28. 28.896 − 699 =
29. 29.996 − 197 =
30. 30.877 − 519 =
31. 31.456 − 237 =
32. 32.289 − 127 =
33. 33.749 − 698 =
34. 34.993 − 499 =
35. 35.729 − 399 =
36. 36.828 − 218 =
37. 37.577 − 119 =
38. 38.771 − 649 =
39. 39.910 − 697 =
40. 40.969 − 487 =

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