Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 226 · 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. 1.567 − 498 =
2. 2.490 − 199 =
3. 3.533 − 149 =
4. 4.757 − 119 =
5. 5.877 − 169 =
6. 6.361 − 197 =
7. 7.453 − 198 =
8. 8.547 − 479 =
9. 9.508 − 368 =
10. 10.843 − 599 =
11. 11.886 − 599 =
12. 12.710 − 299 =
13. 13.948 − 499 =
14. 14.973 − 598 =
15. 15.901 − 398 =
16. 16.813 − 698 =
17. 17.911 − 499 =
18. 18.636 − 479 =
19. 19.664 − 199 =
20. 20.974 − 298 =
21. 21.400 − 219 =
22. 22.371 − 299 =
23. 23.952 − 799 =
24. 24.913 − 797 =
25. 25.298 − 219 =
26. 26.999 − 269 =
27. 27.828 − 799 =
28. 28.752 − 197 =
29. 29.717 − 698 =
30. 30.776 − 678 =
31. 31.883 − 278 =
32. 32.794 − 498 =
33. 33.622 − 249 =
34. 34.516 − 298 =
35. 35.921 − 798 =
36. 36.946 − 577 =
37. 37.925 − 199 =
38. 38.673 − 298 =
39. 39.912 − 209 =
40. 40.549 − 299 =

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