Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 717 · 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. 1.922 − 497 =
2. 2.885 − 299 =
3. 3.854 − 477 =
4. 4.512 − 419 =
5. 5.521 − 497 =
6. 6.764 − 297 =
7. 7.824 − 638 =
8. 8.905 − 198 =
9. 9.247 − 159 =
10. 10.547 − 249 =
11. 11.936 − 298 =
12. 12.617 − 448 =
13. 13.906 − 587 =
14. 14.756 − 199 =
15. 15.623 − 499 =
16. 16.556 − 499 =
17. 17.998 − 699 =
18. 18.684 − 298 =
19. 19.347 − 249 =
20. 20.515 − 297 =
21. 21.743 − 599 =
22. 22.596 − 199 =
23. 23.772 − 588 =
24. 24.885 − 398 =
25. 25.323 − 299 =
26. 26.304 − 197 =
27. 27.626 − 297 =
28. 28.841 − 799 =
29. 29.943 − 497 =
30. 30.706 − 619 =
31. 31.313 − 169 =
32. 32.727 − 408 =
33. 33.517 − 399 =
34. 34.789 − 157 =
35. 35.482 − 198 =
36. 36.934 − 699 =
37. 37.955 − 697 =
38. 38.476 − 338 =
39. 39.688 − 219 =
40. 40.827 − 498 =

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