Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 443 · 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. 1.811 − 478 =
2. 2.694 − 277 =
3. 3.948 − 697 =
4. 4.689 − 298 =
5. 5.283 − 198 =
6. 6.887 − 248 =
7. 7.887 − 449 =
8. 8.393 − 297 =
9. 9.741 − 497 =
10. 10.860 − 338 =
11. 11.532 − 198 =
12. 12.826 − 799 =
13. 13.314 − 299 =
14. 14.804 − 698 =
15. 15.827 − 598 =
16. 16.748 − 158 =
17. 17.898 − 799 =
18. 18.998 − 799 =
19. 19.966 − 597 =
20. 20.985 − 649 =
21. 21.989 − 658 =
22. 22.631 − 517 =
23. 23.900 − 299 =
24. 24.690 − 299 =
25. 25.945 − 309 =
26. 26.774 − 598 =
27. 27.642 − 587 =
28. 28.954 − 799 =
29. 29.706 − 428 =
30. 30.600 − 439 =
31. 31.907 − 198 =
32. 32.920 − 599 =
33. 33.750 − 298 =
34. 34.907 − 598 =
35. 35.645 − 227 =
36. 36.872 − 797 =
37. 37.819 − 399 =
38. 38.963 − 699 =
39. 39.710 − 339 =
40. 40.984 − 297 =

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