Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 57 · 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. 1.571 − 168 =
2. 2.806 − 498 =
3. 3.936 − 798 =
4. 4.744 − 389 =
5. 5.903 − 179 =
6. 6.813 − 599 =
7. 7.547 − 459 =
8. 8.756 − 679 =
9. 9.749 − 319 =
10. 10.987 − 408 =
11. 11.711 − 659 =
12. 12.859 − 598 =
13. 13.849 − 297 =
14. 14.735 − 227 =
15. 15.652 − 119 =
16. 16.717 − 648 =
17. 17.429 − 199 =
18. 18.759 − 167 =
19. 19.866 − 799 =
20. 20.657 − 118 =
21. 21.774 − 498 =
22. 22.796 − 599 =
23. 23.872 − 627 =
24. 24.879 − 599 =
25. 25.594 − 397 =
26. 26.860 − 578 =
27. 27.958 − 799 =
28. 28.862 − 598 =
29. 29.324 − 197 =
30. 30.928 − 257 =
31. 31.960 − 799 =
32. 32.915 − 167 =
33. 33.837 − 229 =
34. 34.454 − 397 =
35. 35.418 − 399 =
36. 36.239 − 158 =
37. 37.878 − 599 =
38. 38.708 − 198 =
39. 39.950 − 499 =
40. 40.918 − 699 =

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