Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 195 · 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. 1.586 − 437 =
2. 2.808 − 599 =
3. 3.687 − 447 =
4. 4.916 − 169 =
5. 5.993 − 297 =
6. 6.588 − 349 =
7. 7.436 − 298 =
8. 8.841 − 497 =
9. 9.438 − 267 =
10. 10.903 − 498 =
11. 11.747 − 599 =
12. 12.939 − 557 =
13. 13.664 − 198 =
14. 14.694 − 498 =
15. 15.739 − 239 =
16. 16.974 − 617 =
17. 17.763 − 497 =
18. 18.404 − 158 =
19. 19.799 − 499 =
20. 20.813 − 447 =
21. 21.653 − 398 =
22. 22.407 − 147 =
23. 23.409 − 217 =
24. 24.489 − 299 =
25. 25.951 − 419 =
26. 26.870 − 699 =
27. 27.614 − 197 =
28. 28.887 − 597 =
29. 29.944 − 438 =
30. 30.381 − 297 =
31. 31.892 − 478 =
32. 32.325 − 199 =
33. 33.933 − 797 =
34. 34.999 − 499 =
35. 35.980 − 497 =
36. 36.827 − 629 =
37. 37.658 − 598 =
38. 38.548 − 297 =
39. 39.684 − 599 =
40. 40.987 − 529 =

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