Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 8 · 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. 1.691 − 298 =
2. 2.531 − 198 =
3. 3.587 − 437 =
4. 4.291 − 149 =
5. 5.998 − 699 =
6. 6.847 − 799 =
7. 7.436 − 398 =
8. 8.924 − 397 =
9. 9.372 − 309 =
10. 10.512 − 499 =
11. 11.539 − 448 =
12. 12.891 − 598 =
13. 13.926 − 248 =
14. 14.763 − 599 =
15. 15.509 − 297 =
16. 16.448 − 399 =
17. 17.685 − 497 =
18. 18.604 − 499 =
19. 19.732 − 519 =
20. 20.222 − 199 =
21. 21.779 − 227 =
22. 22.580 − 398 =
23. 23.959 − 699 =
24. 24.903 − 699 =
25. 25.952 − 677 =
26. 26.829 − 399 =
27. 27.844 − 177 =
28. 28.666 − 447 =
29. 29.863 − 598 =
30. 30.612 − 247 =
31. 31.475 − 397 =
32. 32.398 − 199 =
33. 33.592 − 397 =
34. 34.547 − 399 =
35. 35.923 − 798 =
36. 36.829 − 798 =
37. 37.781 − 299 =
38. 38.995 − 357 =
39. 39.768 − 389 =
40. 40.941 − 299 =

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