Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 180 · 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. 1.800 − 499 =
2. 2.645 − 487 =
3. 3.808 − 408 =
4. 4.834 − 289 =
5. 5.528 − 509 =
6. 6.569 − 199 =
7. 7.929 − 619 =
8. 8.529 − 498 =
9. 9.896 − 659 =
10. 10.538 − 229 =
11. 11.793 − 227 =
12. 12.560 − 199 =
13. 13.643 − 397 =
14. 14.614 − 338 =
15. 15.884 − 698 =
16. 16.672 − 498 =
17. 17.649 − 198 =
18. 18.855 − 798 =
19. 19.867 − 798 =
20. 20.541 − 199 =
21. 21.343 − 199 =
22. 22.933 − 797 =
23. 23.844 − 619 =
24. 24.983 − 318 =
25. 25.792 − 128 =
26. 26.684 − 647 =
27. 27.963 − 699 =
28. 28.696 − 497 =
29. 29.524 − 297 =
30. 30.924 − 608 =
31. 31.276 − 197 =
32. 32.783 − 199 =
33. 33.785 − 669 =
34. 34.817 − 659 =
35. 35.571 − 117 =
36. 36.932 − 637 =
37. 37.813 − 527 =
38. 38.930 − 498 =
39. 39.934 − 799 =
40. 40.352 − 309 =

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