Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 765 · 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. 1.830 − 199 =
2. 2.710 − 617 =
3. 3.628 − 429 =
4. 4.642 − 337 =
5. 5.433 − 199 =
6. 6.777 − 497 =
7. 7.694 − 199 =
8. 8.437 − 219 =
9. 9.620 − 497 =
10. 10.331 − 197 =
11. 11.469 − 298 =
12. 12.569 − 379 =
13. 13.638 − 597 =
14. 14.889 − 398 =
15. 15.506 − 197 =
16. 16.760 − 597 =
17. 17.856 − 498 =
18. 18.974 − 499 =
19. 19.637 − 387 =
20. 20.994 − 697 =
21. 21.945 − 797 =
22. 22.848 − 498 =
23. 23.773 − 299 =
24. 24.778 − 699 =
25. 25.364 − 229 =
26. 26.734 − 299 =
27. 27.752 − 298 =
28. 28.260 − 157 =
29. 29.490 − 298 =
30. 30.783 − 268 =
31. 31.805 − 337 =
32. 32.841 − 799 =
33. 33.963 − 169 =
34. 34.600 − 498 =
35. 35.697 − 478 =
36. 36.722 − 638 =
37. 37.979 − 347 =
38. 38.819 − 499 =
39. 39.838 − 399 =
40. 40.355 − 299 =

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