Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 288 · 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. 1.598 − 308 =
2. 2.829 − 297 =
3. 3.495 − 398 =
4. 4.489 − 347 =
5. 5.953 − 279 =
6. 6.918 − 599 =
7. 7.691 − 497 =
8. 8.786 − 698 =
9. 9.681 − 297 =
10. 10.652 − 197 =
11. 11.527 − 227 =
12. 12.889 − 338 =
13. 13.829 − 398 =
14. 14.776 − 577 =
15. 15.816 − 699 =
16. 16.772 − 599 =
17. 17.717 − 497 =
18. 18.822 − 137 =
19. 19.606 − 497 =
20. 20.668 − 298 =
21. 21.776 − 398 =
22. 22.903 − 799 =
23. 23.945 − 589 =
24. 24.459 − 379 =
25. 25.944 − 507 =
26. 26.877 − 798 =
27. 27.340 − 297 =
28. 28.616 − 518 =
29. 29.441 − 397 =
30. 30.779 − 599 =
31. 31.828 − 797 =
32. 32.909 − 497 =
33. 33.263 − 198 =
34. 34.838 − 799 =
35. 35.920 − 508 =
36. 36.737 − 398 =
37. 37.732 − 698 =
38. 38.859 − 798 =
39. 39.898 − 798 =
40. 40.790 − 697 =

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