Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 544 · 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. 1.584 − 499 =
2. 2.710 − 279 =
3. 3.827 − 649 =
4. 4.380 − 298 =
5. 5.892 − 397 =
6. 6.625 − 598 =
7. 7.663 − 557 =
8. 8.554 − 129 =
9. 9.379 − 297 =
10. 10.758 − 119 =
11. 11.380 − 147 =
12. 12.791 − 299 =
13. 13.963 − 798 =
14. 14.530 − 497 =
15. 15.936 − 797 =
16. 16.565 − 439 =
17. 17.969 − 798 =
18. 18.886 − 799 =
19. 19.905 − 469 =
20. 20.451 − 198 =
21. 21.816 − 797 =
22. 22.704 − 498 =
23. 23.566 − 498 =
24. 24.717 − 329 =
25. 25.695 − 597 =
26. 26.989 − 798 =
27. 27.587 − 129 =
28. 28.663 − 559 =
29. 29.368 − 197 =
30. 30.866 − 698 =
31. 31.906 − 799 =
32. 32.770 − 437 =
33. 33.993 − 427 =
34. 34.480 − 437 =
35. 35.319 − 298 =
36. 36.738 − 398 =
37. 37.815 − 299 =
38. 38.361 − 287 =
39. 39.360 − 229 =
40. 40.687 − 617 =

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