Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 821 · 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. 1.732 − 699 =
2. 2.939 − 697 =
3. 3.626 − 499 =
4. 4.733 − 309 =
5. 5.859 − 459 =
6. 6.476 − 257 =
7. 7.783 − 687 =
8. 8.476 − 218 =
9. 9.823 − 799 =
10. 10.947 − 797 =
11. 11.815 − 797 =
12. 12.960 − 338 =
13. 13.941 − 497 =
14. 14.756 − 597 =
15. 15.594 − 127 =
16. 16.651 − 499 =
17. 17.839 − 799 =
18. 18.457 − 139 =
19. 19.802 − 699 =
20. 20.842 − 599 =
21. 21.385 − 227 =
22. 22.511 − 297 =
23. 23.224 − 199 =
24. 24.365 − 287 =
25. 25.880 − 799 =
26. 26.732 − 597 =
27. 27.987 − 399 =
28. 28.364 − 347 =
29. 29.955 − 797 =
30. 30.941 − 597 =
31. 31.790 − 497 =
32. 32.765 − 299 =
33. 33.971 − 669 =
34. 34.507 − 338 =
35. 35.569 − 499 =
36. 36.227 − 119 =
37. 37.731 − 398 =
38. 38.872 − 499 =
39. 39.434 − 197 =
40. 40.768 − 597 =

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