Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 901 · 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. 1.472 − 148 =
2. 2.971 − 599 =
3. 3.741 − 697 =
4. 4.639 − 357 =
5. 5.836 − 698 =
6. 6.955 − 298 =
7. 7.994 − 537 =
8. 8.441 − 249 =
9. 9.331 − 298 =
10. 10.437 − 308 =
11. 11.977 − 598 =
12. 12.834 − 598 =
13. 13.976 − 797 =
14. 14.395 − 349 =
15. 15.555 − 398 =
16. 16.670 − 457 =
17. 17.403 − 299 =
18. 18.902 − 599 =
19. 19.182 − 129 =
20. 20.905 − 498 =
21. 21.786 − 659 =
22. 22.764 − 278 =
23. 23.442 − 427 =
24. 24.728 − 399 =
25. 25.735 − 159 =
26. 26.991 − 628 =
27. 27.959 − 798 =
28. 28.949 − 489 =
29. 29.619 − 147 =
30. 30.636 − 489 =
31. 31.775 − 599 =
32. 32.944 − 627 =
33. 33.996 − 597 =
34. 34.985 − 497 =
35. 35.646 − 597 =
36. 36.553 − 497 =
37. 37.809 − 499 =
38. 38.743 − 168 =
39. 39.383 − 199 =
40. 40.789 − 117 =

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