Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 928 · 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. 1.648 − 398 =
2. 2.613 − 299 =
3. 3.803 − 298 =
4. 4.969 − 397 =
5. 5.628 − 568 =
6. 6.640 − 138 =
7. 7.911 − 249 =
8. 8.403 − 297 =
9. 9.754 − 199 =
10. 10.296 − 198 =
11. 11.734 − 207 =
12. 12.868 − 577 =
13. 13.688 − 297 =
14. 14.791 − 689 =
15. 15.706 − 247 =
16. 16.501 − 398 =
17. 17.713 − 579 =
18. 18.845 − 799 =
19. 19.402 − 389 =
20. 20.682 − 207 =
21. 21.917 − 699 =
22. 22.947 − 499 =
23. 23.411 − 298 =
24. 24.661 − 599 =
25. 25.462 − 217 =
26. 26.955 − 497 =
27. 27.862 − 799 =
28. 28.471 − 399 =
29. 29.407 − 199 =
30. 30.891 − 608 =
31. 31.919 − 399 =
32. 32.834 − 499 =
33. 33.454 − 199 =
34. 34.876 − 198 =
35. 35.938 − 597 =
36. 36.938 − 797 =
37. 37.819 − 697 =
38. 38.758 − 597 =
39. 39.921 − 498 =
40. 40.725 − 267 =

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