Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 62 · 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. 1.895 − 797 =
2. 2.816 − 798 =
3. 3.583 − 399 =
4. 4.773 − 699 =
5. 5.611 − 297 =
6. 6.665 − 599 =
7. 7.623 − 538 =
8. 8.829 − 297 =
9. 9.833 − 797 =
10. 10.947 − 607 =
11. 11.722 − 397 =
12. 12.391 − 198 =
13. 13.819 − 197 =
14. 14.797 − 699 =
15. 15.528 − 497 =
16. 16.536 − 497 =
17. 17.924 − 628 =
18. 18.846 − 348 =
19. 19.731 − 558 =
20. 20.730 − 198 =
21. 21.904 − 478 =
22. 22.848 − 599 =
23. 23.675 − 578 =
24. 24.838 − 337 =
25. 25.891 − 398 =
26. 26.412 − 367 =
27. 27.620 − 598 =
28. 28.549 − 508 =
29. 29.569 − 487 =
30. 30.435 − 297 =
31. 31.238 − 199 =
32. 32.670 − 449 =
33. 33.436 − 149 =
34. 34.737 − 607 =
35. 35.239 − 179 =
36. 36.884 − 197 =
37. 37.356 − 209 =
38. 38.825 − 567 =
39. 39.899 − 197 =
40. 40.759 − 349 =

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