Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 32 · 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. 1.514 − 398 =
2. 2.425 − 297 =
3. 3.610 − 128 =
4. 4.582 − 247 =
5. 5.997 − 449 =
6. 6.911 − 799 =
7. 7.486 − 149 =
8. 8.993 − 577 =
9. 9.659 − 497 =
10. 10.734 − 598 =
11. 11.943 − 608 =
12. 12.813 − 798 =
13. 13.972 − 668 =
14. 14.990 − 277 =
15. 15.598 − 398 =
16. 16.681 − 398 =
17. 17.744 − 639 =
18. 18.679 − 199 =
19. 19.848 − 798 =
20. 20.654 − 599 =
21. 21.691 − 598 =
22. 22.639 − 137 =
23. 23.735 − 299 =
24. 24.554 − 528 =
25. 25.702 − 197 =
26. 26.729 − 698 =
27. 27.812 − 599 =
28. 28.974 − 599 =
29. 29.452 − 389 =
30. 30.904 − 697 =
31. 31.486 − 398 =
32. 32.313 − 287 =
33. 33.611 − 527 =
34. 34.482 − 167 =
35. 35.494 − 397 =
36. 36.791 − 197 =
37. 37.824 − 598 =
38. 38.730 − 499 =
39. 39.675 − 498 =
40. 40.741 − 598 =

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