Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 388 · 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. 1.697 − 118 =
2. 2.523 − 499 =
3. 3.884 − 697 =
4. 4.949 − 699 =
5. 5.704 − 437 =
6. 6.977 − 498 =
7. 7.791 − 539 =
8. 8.605 − 397 =
9. 9.584 − 239 =
10. 10.403 − 309 =
11. 11.951 − 398 =
12. 12.781 − 199 =
13. 13.683 − 498 =
14. 14.660 − 589 =
15. 15.607 − 159 =
16. 16.298 − 199 =
17. 17.910 − 229 =
18. 18.815 − 798 =
19. 19.409 − 199 =
20. 20.812 − 397 =
21. 21.990 − 798 =
22. 22.750 − 697 =
23. 23.441 − 197 =
24. 24.575 − 139 =
25. 25.748 − 297 =
26. 26.839 − 797 =
27. 27.423 − 258 =
28. 28.935 − 797 =
29. 29.321 − 199 =
30. 30.677 − 497 =
31. 31.844 − 697 =
32. 32.741 − 599 =
33. 33.941 − 548 =
34. 34.485 − 297 =
35. 35.575 − 497 =
36. 36.608 − 498 =
37. 37.595 − 157 =
38. 38.817 − 257 =
39. 39.443 − 398 =
40. 40.832 − 697 =

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