Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 79 · 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. 1.969 − 798 =
2. 2.776 − 398 =
3. 3.298 − 259 =
4. 4.825 − 798 =
5. 5.255 − 199 =
6. 6.525 − 487 =
7. 7.653 − 398 =
8. 8.457 − 198 =
9. 9.805 − 299 =
10. 10.540 − 497 =
11. 11.747 − 298 =
12. 12.831 − 398 =
13. 13.514 − 498 =
14. 14.534 − 379 =
15. 15.977 − 797 =
16. 16.299 − 137 =
17. 17.477 − 419 =
18. 18.704 − 338 =
19. 19.999 − 317 =
20. 20.905 − 697 =
21. 21.797 − 598 =
22. 22.965 − 699 =
23. 23.737 − 697 =
24. 24.981 − 548 =
25. 25.752 − 699 =
26. 26.602 − 499 =
27. 27.728 − 369 =
28. 28.751 − 137 =
29. 29.972 − 668 =
30. 30.777 − 278 =
31. 31.971 − 429 =
32. 32.738 − 339 =
33. 33.839 − 799 =
34. 34.932 − 797 =
35. 35.975 − 297 =
36. 36.832 − 327 =
37. 37.982 − 498 =
38. 38.853 − 798 =
39. 39.775 − 569 =
40. 40.766 − 699 =

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