Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 683 · 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. 1.985 − 279 =
2. 2.241 − 209 =
3. 3.899 − 649 =
4. 4.896 − 599 =
5. 5.979 − 659 =
6. 6.948 − 799 =
7. 7.399 − 158 =
8. 8.774 − 699 =
9. 9.886 − 799 =
10. 10.634 − 497 =
11. 11.941 − 397 =
12. 12.736 − 637 =
13. 13.753 − 507 =
14. 14.827 − 799 =
15. 15.674 − 549 =
16. 16.900 − 799 =
17. 17.441 − 249 =
18. 18.380 − 337 =
19. 19.751 − 698 =
20. 20.482 − 389 =
21. 21.644 − 209 =
22. 22.823 − 199 =
23. 23.843 − 579 =
24. 24.877 − 599 =
25. 25.566 − 499 =
26. 26.930 − 499 =
27. 27.999 − 398 =
28. 28.725 − 397 =
29. 29.623 − 497 =
30. 30.867 − 457 =
31. 31.557 − 399 =
32. 32.835 − 798 =
33. 33.995 − 599 =
34. 34.409 − 299 =
35. 35.770 − 499 =
36. 36.546 − 197 =
37. 37.787 − 299 =
38. 38.607 − 148 =
39. 39.544 − 399 =
40. 40.985 − 498 =

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