Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 83 · 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. 1.702 − 259 =
2. 2.313 − 298 =
3. 3.958 − 557 =
4. 4.640 − 209 =
5. 5.583 − 499 =
6. 6.389 − 297 =
7. 7.323 − 268 =
8. 8.570 − 157 =
9. 9.430 − 138 =
10. 10.312 − 259 =
11. 11.898 − 799 =
12. 12.789 − 348 =
13. 13.894 − 217 =
14. 14.916 − 198 =
15. 15.782 − 397 =
16. 16.711 − 397 =
17. 17.766 − 397 =
18. 18.571 − 397 =
19. 19.586 − 339 =
20. 20.904 − 697 =
21. 21.850 − 249 =
22. 22.918 − 357 =
23. 23.767 − 369 =
24. 24.527 − 199 =
25. 25.711 − 497 =
26. 26.422 − 397 =
27. 27.684 − 139 =
28. 28.462 − 357 =
29. 29.777 − 699 =
30. 30.603 − 298 =
31. 31.738 − 649 =
32. 32.648 − 298 =
33. 33.978 − 197 =
34. 34.568 − 299 =
35. 35.599 − 348 =
36. 36.968 − 118 =
37. 37.786 − 617 =
38. 38.888 − 799 =
39. 39.867 − 687 =
40. 40.462 − 297 =

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