Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 548 · 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. 1.579 − 299 =
2. 2.779 − 299 =
3. 3.662 − 599 =
4. 4.779 − 119 =
5. 5.570 − 487 =
6. 6.847 − 797 =
7. 7.476 − 199 =
8. 8.621 − 397 =
9. 9.377 − 199 =
10. 10.811 − 199 =
11. 11.419 − 399 =
12. 12.968 − 509 =
13. 13.744 − 397 =
14. 14.397 − 298 =
15. 15.955 − 697 =
16. 16.590 − 399 =
17. 17.674 − 597 =
18. 18.830 − 498 =
19. 19.632 − 499 =
20. 20.361 − 299 =
21. 21.672 − 599 =
22. 22.766 − 477 =
23. 23.742 − 559 =
24. 24.524 − 198 =
25. 25.748 − 669 =
26. 26.922 − 698 =
27. 27.254 − 127 =
28. 28.465 − 398 =
29. 29.846 − 699 =
30. 30.642 − 317 =
31. 31.655 − 197 =
32. 32.781 − 549 =
33. 33.548 − 199 =
34. 34.565 − 399 =
35. 35.182 − 118 =
36. 36.256 − 197 =
37. 37.995 − 397 =
38. 38.934 − 527 =
39. 39.653 − 598 =
40. 40.906 − 337 =

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