Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 920 · 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. 1.504 − 147 =
2. 2.801 − 599 =
3. 3.867 − 797 =
4. 4.669 − 598 =
5. 5.936 − 527 =
6. 6.474 − 298 =
7. 7.860 − 249 =
8. 8.507 − 299 =
9. 9.470 − 197 =
10. 10.832 − 667 =
11. 11.634 − 598 =
12. 12.775 − 698 =
13. 13.952 − 599 =
14. 14.713 − 157 =
15. 15.853 − 199 =
16. 16.993 − 799 =
17. 17.697 − 498 =
18. 18.781 − 197 =
19. 19.376 − 238 =
20. 20.859 − 797 =
21. 21.614 − 199 =
22. 22.836 − 798 =
23. 23.865 − 799 =
24. 24.734 − 399 =
25. 25.372 − 198 =
26. 26.401 − 268 =
27. 27.240 − 197 =
28. 28.867 − 398 =
29. 29.866 − 637 =
30. 30.996 − 598 =
31. 31.820 − 799 =
32. 32.977 − 199 =
33. 33.624 − 599 =
34. 34.715 − 548 =
35. 35.684 − 498 =
36. 36.532 − 189 =
37. 37.638 − 227 =
38. 38.975 − 599 =
39. 39.769 − 169 =
40. 40.548 − 397 =

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