Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 888 · 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. 1.618 − 499 =
2. 2.977 − 798 =
3. 3.827 − 417 =
4. 4.781 − 298 =
5. 5.342 − 168 =
6. 6.879 − 798 =
7. 7.713 − 537 =
8. 8.886 − 499 =
9. 9.343 − 297 =
10. 10.904 − 199 =
11. 11.744 − 198 =
12. 12.714 − 597 =
13. 13.362 − 197 =
14. 14.944 − 599 =
15. 15.499 − 457 =
16. 16.935 − 558 =
17. 17.992 − 607 =
18. 18.755 − 499 =
19. 19.250 − 169 =
20. 20.902 − 599 =
21. 21.887 − 148 =
22. 22.830 − 497 =
23. 23.591 − 197 =
24. 24.919 − 128 =
25. 25.640 − 119 =
26. 26.773 − 698 =
27. 27.574 − 258 =
28. 28.664 − 197 =
29. 29.908 − 597 =
30. 30.841 − 797 =
31. 31.753 − 259 =
32. 32.879 − 397 =
33. 33.812 − 598 =
34. 34.987 − 399 =
35. 35.999 − 798 =
36. 36.667 − 588 =
37. 37.397 − 197 =
38. 38.896 − 198 =
39. 39.546 − 298 =
40. 40.857 − 697 =

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