Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 892 · 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. 1.894 − 248 =
2. 2.921 − 649 =
3. 3.523 − 199 =
4. 4.940 − 399 =
5. 5.598 − 447 =
6. 6.588 − 499 =
7. 7.930 − 207 =
8. 8.588 − 198 =
9. 9.512 − 499 =
10. 10.893 − 698 =
11. 11.590 − 198 =
12. 12.794 − 617 =
13. 13.841 − 798 =
14. 14.908 − 697 =
15. 15.833 − 368 =
16. 16.763 − 379 =
17. 17.804 − 197 =
18. 18.877 − 798 =
19. 19.790 − 699 =
20. 20.522 − 297 =
21. 21.981 − 307 =
22. 22.553 − 209 =
23. 23.917 − 679 =
24. 24.305 − 208 =
25. 25.623 − 299 =
26. 26.556 − 397 =
27. 27.884 − 598 =
28. 28.597 − 379 =
29. 29.878 − 699 =
30. 30.333 − 197 =
31. 31.922 − 197 =
32. 32.920 − 797 =
33. 33.964 − 138 =
34. 34.759 − 698 =
35. 35.724 − 629 =
36. 36.499 − 287 =
37. 37.254 − 198 =
38. 38.527 − 398 =
39. 39.822 − 799 =
40. 40.893 − 598 =

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