Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 123 · 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. 1.879 − 168 =
2. 2.547 − 307 =
3. 3.802 − 699 =
4. 4.995 − 367 =
5. 5.742 − 499 =
6. 6.416 − 278 =
7. 7.682 − 647 =
8. 8.397 − 199 =
9. 9.637 − 399 =
10. 10.676 − 599 =
11. 11.426 − 198 =
12. 12.825 − 598 =
13. 13.248 − 199 =
14. 14.803 − 197 =
15. 15.306 − 159 =
16. 16.817 − 798 =
17. 17.581 − 298 =
18. 18.550 − 497 =
19. 19.674 − 199 =
20. 20.543 − 497 =
21. 21.917 − 399 =
22. 22.525 − 329 =
23. 23.761 − 369 =
24. 24.966 − 799 =
25. 25.887 − 697 =
26. 26.813 − 699 =
27. 27.901 − 598 =
28. 28.622 − 229 =
29. 29.659 − 498 =
30. 30.467 − 449 =
31. 31.659 − 559 =
32. 32.672 − 497 =
33. 33.657 − 497 =
34. 34.618 − 397 =
35. 35.778 − 678 =
36. 36.611 − 297 =
37. 37.913 − 699 =
38. 38.942 − 609 =
39. 39.357 − 209 =
40. 40.684 − 339 =

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