Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 320 · 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. 1.718 − 288 =
2. 2.992 − 547 =
3. 3.825 − 677 =
4. 4.602 − 399 =
5. 5.833 − 237 =
6. 6.970 − 568 =
7. 7.722 − 139 =
8. 8.786 − 198 =
9. 9.618 − 478 =
10. 10.983 − 158 =
11. 11.738 − 358 =
12. 12.479 − 149 =
13. 13.664 − 637 =
14. 14.539 − 498 =
15. 15.422 − 207 =
16. 16.441 − 399 =
17. 17.529 − 498 =
18. 18.624 − 608 =
19. 19.490 − 378 =
20. 20.969 − 799 =
21. 21.925 − 799 =
22. 22.586 − 469 =
23. 23.964 − 197 =
24. 24.651 − 228 =
25. 25.901 − 548 =
26. 26.856 − 799 =
27. 27.797 − 599 =
28. 28.676 − 128 =
29. 29.763 − 649 =
30. 30.446 − 297 =
31. 31.681 − 637 =
32. 32.844 − 299 =
33. 33.943 − 698 =
34. 34.729 − 297 =
35. 35.646 − 387 =
36. 36.777 − 397 =
37. 37.495 − 337 =
38. 38.813 − 798 =
39. 39.987 − 197 =
40. 40.524 − 419 =

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