Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 184 · 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. 1.823 − 658 =
2. 2.635 − 518 =
3. 3.761 − 127 =
4. 4.698 − 198 =
5. 5.614 − 399 =
6. 6.216 − 139 =
7. 7.349 − 197 =
8. 8.779 − 497 =
9. 9.760 − 589 =
10. 10.556 − 179 =
11. 11.426 − 218 =
12. 12.822 − 697 =
13. 13.809 − 568 =
14. 14.270 − 157 =
15. 15.682 − 217 =
16. 16.965 − 698 =
17. 17.564 − 319 =
18. 18.929 − 198 =
19. 19.887 − 489 =
20. 20.692 − 199 =
21. 21.472 − 199 =
22. 22.575 − 348 =
23. 23.887 − 219 =
24. 24.797 − 149 =
25. 25.550 − 198 =
26. 26.565 − 199 =
27. 27.884 − 308 =
28. 28.851 − 219 =
29. 29.806 − 499 =
30. 30.294 − 279 =
31. 31.726 − 518 =
32. 32.878 − 477 =
33. 33.987 − 397 =
34. 34.659 − 297 =
35. 35.553 − 138 =
36. 36.696 − 599 =
37. 37.710 − 207 =
38. 38.639 − 499 =
39. 39.676 − 399 =
40. 40.892 − 798 =

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