Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 958 · 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. 1.692 − 319 =
2. 2.529 − 499 =
3. 3.903 − 188 =
4. 4.699 − 297 =
5. 5.893 − 539 =
6. 6.746 − 699 =
7. 7.768 − 499 =
8. 8.364 − 307 =
9. 9.502 − 379 =
10. 10.919 − 299 =
11. 11.947 − 447 =
12. 12.905 − 118 =
13. 13.731 − 687 =
14. 14.574 − 398 =
15. 15.742 − 348 =
16. 16.704 − 598 =
17. 17.993 − 599 =
18. 18.771 − 697 =
19. 19.538 − 257 =
20. 20.757 − 197 =
21. 21.949 − 599 =
22. 22.664 − 307 =
23. 23.411 − 237 =
24. 24.624 − 598 =
25. 25.894 − 599 =
26. 26.689 − 317 =
27. 27.935 − 398 =
28. 28.872 − 169 =
29. 29.919 − 447 =
30. 30.676 − 588 =
31. 31.784 − 288 =
32. 32.781 − 597 =
33. 33.644 − 499 =
34. 34.974 − 117 =
35. 35.641 − 397 =
36. 36.944 − 379 =
37. 37.647 − 219 =
38. 38.685 − 497 =
39. 39.418 − 299 =
40. 40.404 − 358 =

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