Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 817 · 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. 1.419 − 299 =
2. 2.992 − 698 =
3. 3.596 − 297 =
4. 4.752 − 698 =
5. 5.317 − 247 =
6. 6.764 − 407 =
7. 7.863 − 688 =
8. 8.768 − 299 =
9. 9.700 − 529 =
10. 10.578 − 179 =
11. 11.611 − 477 =
12. 12.645 − 498 =
13. 13.524 − 498 =
14. 14.860 − 158 =
15. 15.449 − 297 =
16. 16.882 − 539 =
17. 17.767 − 699 =
18. 18.962 − 798 =
19. 19.446 − 169 =
20. 20.898 − 799 =
21. 21.669 − 498 =
22. 22.415 − 397 =
23. 23.700 − 569 =
24. 24.888 − 589 =
25. 25.549 − 409 =
26. 26.937 − 119 =
27. 27.750 − 697 =
28. 28.919 − 598 =
29. 29.422 − 198 =
30. 30.279 − 229 =
31. 31.978 − 598 =
32. 32.912 − 549 =
33. 33.704 − 597 =
34. 34.448 − 428 =
35. 35.738 − 647 =
36. 36.905 − 799 =
37. 37.689 − 648 =
38. 38.764 − 698 =
39. 39.571 − 298 =
40. 40.960 − 258 =

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