Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 278 · 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. 1.890 − 539 =
2. 2.234 − 158 =
3. 3.620 − 168 =
4. 4.348 − 298 =
5. 5.937 − 437 =
6. 6.438 − 197 =
7. 7.830 − 518 =
8. 8.538 − 257 =
9. 9.677 − 177 =
10. 10.739 − 379 =
11. 11.610 − 439 =
12. 12.536 − 397 =
13. 13.403 − 128 =
14. 14.677 − 499 =
15. 15.913 − 549 =
16. 16.718 − 519 =
17. 17.808 − 198 =
18. 18.831 − 499 =
19. 19.652 − 117 =
20. 20.830 − 508 =
21. 21.338 − 198 =
22. 22.835 − 697 =
23. 23.911 − 499 =
24. 24.786 − 608 =
25. 25.880 − 398 =
26. 26.973 − 699 =
27. 27.889 − 297 =
28. 28.954 − 598 =
29. 29.825 − 197 =
30. 30.827 − 499 =
31. 31.770 − 609 =
32. 32.955 − 599 =
33. 33.896 − 798 =
34. 34.623 − 577 =
35. 35.837 − 798 =
36. 36.964 − 699 =
37. 37.900 − 197 =
38. 38.857 − 208 =
39. 39.866 − 399 =
40. 40.716 − 697 =

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