Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 651 · 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. 1.589 − 249 =
2. 2.820 − 699 =
3. 3.813 − 189 =
4. 4.628 − 299 =
5. 5.599 − 499 =
6. 6.849 − 598 =
7. 7.734 − 597 =
8. 8.828 − 798 =
9. 9.965 − 398 =
10. 10.457 − 369 =
11. 11.906 − 167 =
12. 12.750 − 598 =
13. 13.881 − 599 =
14. 14.970 − 497 =
15. 15.243 − 148 =
16. 16.805 − 597 =
17. 17.562 − 358 =
18. 18.645 − 338 =
19. 19.373 − 197 =
20. 20.683 − 399 =
21. 21.807 − 697 =
22. 22.907 − 647 =
23. 23.382 − 297 =
24. 24.823 − 399 =
25. 25.489 − 297 =
26. 26.880 − 409 =
27. 27.440 − 198 =
28. 28.834 − 798 =
29. 29.549 − 398 =
30. 30.839 − 639 =
31. 31.604 − 538 =
32. 32.651 − 598 =
33. 33.758 − 499 =
34. 34.679 − 377 =
35. 35.969 − 297 =
36. 36.940 − 629 =
37. 37.778 − 197 =
38. 38.710 − 299 =
39. 39.754 − 199 =
40. 40.753 − 508 =

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