Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 780 · 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. 1.513 − 348 =
2. 2.917 − 199 =
3. 3.470 − 197 =
4. 4.779 − 697 =
5. 5.427 − 397 =
6. 6.455 − 197 =
7. 7.678 − 599 =
8. 8.708 − 207 =
9. 9.961 − 797 =
10. 10.338 − 117 =
11. 11.888 − 799 =
12. 12.929 − 797 =
13. 13.632 − 599 =
14. 14.810 − 568 =
15. 15.931 − 699 =
16. 16.962 − 468 =
17. 17.670 − 299 =
18. 18.498 − 398 =
19. 19.596 − 419 =
20. 20.917 − 159 =
21. 21.862 − 799 =
22. 22.969 − 797 =
23. 23.589 − 279 =
24. 24.935 − 498 =
25. 25.945 − 497 =
26. 26.863 − 207 =
27. 27.529 − 398 =
28. 28.858 − 698 =
29. 29.955 − 799 =
30. 30.993 − 649 =
31. 31.774 − 419 =
32. 32.436 − 397 =
33. 33.908 − 597 =
34. 34.708 − 237 =
35. 35.937 − 799 =
36. 36.772 − 437 =
37. 37.854 − 538 =
38. 38.590 − 358 =
39. 39.948 − 137 =
40. 40.606 − 447 =

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