Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 38 · 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. 1.736 − 158 =
2. 2.229 − 127 =
3. 3.341 − 298 =
4. 4.474 − 287 =
5. 5.946 − 497 =
6. 6.746 − 597 =
7. 7.528 − 199 =
8. 8.900 − 599 =
9. 9.731 − 699 =
10. 10.840 − 498 =
11. 11.852 − 308 =
12. 12.907 − 397 =
13. 13.596 − 398 =
14. 14.488 − 299 =
15. 15.712 − 199 =
16. 16.696 − 629 =
17. 17.999 − 597 =
18. 18.628 − 237 =
19. 19.568 − 397 =
20. 20.758 − 698 =
21. 21.703 − 197 =
22. 22.767 − 577 =
23. 23.903 − 207 =
24. 24.661 − 618 =
25. 25.421 − 399 =
26. 26.560 − 397 =
27. 27.419 − 297 =
28. 28.294 − 219 =
29. 29.869 − 597 =
30. 30.797 − 668 =
31. 31.855 − 797 =
32. 32.368 − 297 =
33. 33.689 − 397 =
34. 34.384 − 197 =
35. 35.730 − 687 =
36. 36.513 − 397 =
37. 37.844 − 398 =
38. 38.942 − 518 =
39. 39.872 − 568 =
40. 40.838 − 298 =

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