Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 344 · 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. 1.727 − 679 =
2. 2.772 − 359 =
3. 3.960 − 589 =
4. 4.870 − 399 =
5. 5.885 − 517 =
6. 6.808 − 198 =
7. 7.959 − 367 =
8. 8.591 − 499 =
9. 9.471 − 387 =
10. 10.587 − 128 =
11. 11.820 − 199 =
12. 12.624 − 398 =
13. 13.873 − 387 =
14. 14.987 − 407 =
15. 15.935 − 197 =
16. 16.681 − 649 =
17. 17.260 − 138 =
18. 18.475 − 217 =
19. 19.427 − 197 =
20. 20.598 − 229 =
21. 21.522 − 399 =
22. 22.907 − 118 =
23. 23.664 − 299 =
24. 24.634 − 389 =
25. 25.941 − 248 =
26. 26.970 − 797 =
27. 27.481 − 207 =
28. 28.901 − 698 =
29. 29.648 − 298 =
30. 30.945 − 258 =
31. 31.213 − 168 =
32. 32.922 − 797 =
33. 33.436 − 418 =
34. 34.669 − 299 =
35. 35.669 − 548 =
36. 36.722 − 698 =
37. 37.969 − 239 =
38. 38.940 − 499 =
39. 39.956 − 599 =
40. 40.959 − 199 =

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