Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 768 · 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. 1.912 − 189 =
2. 2.498 − 397 =
3. 3.683 − 599 =
4. 4.940 − 797 =
5. 5.952 − 397 =
6. 6.539 − 247 =
7. 7.778 − 197 =
8. 8.726 − 687 =
9. 9.722 − 129 =
10. 10.923 − 128 =
11. 11.812 − 799 =
12. 12.479 − 258 =
13. 13.450 − 409 =
14. 14.569 − 298 =
15. 15.923 − 439 =
16. 16.693 − 197 =
17. 17.930 − 299 =
18. 18.524 − 297 =
19. 19.652 − 638 =
20. 20.675 − 609 =
21. 21.672 − 349 =
22. 22.993 − 259 =
23. 23.853 − 799 =
24. 24.265 − 137 =
25. 25.800 − 519 =
26. 26.795 − 539 =
27. 27.358 − 249 =
28. 28.438 − 397 =
29. 29.929 − 498 =
30. 30.772 − 497 =
31. 31.353 − 297 =
32. 32.763 − 399 =
33. 33.879 − 297 =
34. 34.817 − 797 =
35. 35.263 − 218 =
36. 36.980 − 279 =
37. 37.889 − 797 =
38. 38.847 − 659 =
39. 39.780 − 688 =
40. 40.931 − 598 =

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