Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 185 · 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. 1.820 − 158 =
2. 2.767 − 189 =
3. 3.993 − 418 =
4. 4.401 − 157 =
5. 5.849 − 499 =
6. 6.749 − 698 =
7. 7.505 − 367 =
8. 8.604 − 299 =
9. 9.404 − 199 =
10. 10.955 − 799 =
11. 11.493 − 458 =
12. 12.956 − 398 =
13. 13.897 − 798 =
14. 14.644 − 598 =
15. 15.942 − 799 =
16. 16.990 − 797 =
17. 17.973 − 649 =
18. 18.477 − 198 =
19. 19.920 − 279 =
20. 20.857 − 327 =
21. 21.871 − 399 =
22. 22.601 − 527 =
23. 23.597 − 339 =
24. 24.680 − 399 =
25. 25.869 − 797 =
26. 26.861 − 688 =
27. 27.816 − 678 =
28. 28.832 − 649 =
29. 29.999 − 698 =
30. 30.982 − 368 =
31. 31.294 − 157 =
32. 32.334 − 317 =
33. 33.225 − 127 =
34. 34.325 − 298 =
35. 35.789 − 598 =
36. 36.564 − 399 =
37. 37.952 − 298 =
38. 38.773 − 668 =
39. 39.933 − 199 =
40. 40.612 − 348 =

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