Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 793 · 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. 1.677 − 179 =
2. 2.639 − 447 =
3. 3.680 − 298 =
4. 4.831 − 298 =
5. 5.907 − 598 =
6. 6.986 − 699 =
7. 7.785 − 599 =
8. 8.872 − 589 =
9. 9.719 − 297 =
10. 10.422 − 159 =
11. 11.224 − 198 =
12. 12.420 − 297 =
13. 13.798 − 298 =
14. 14.338 − 207 =
15. 15.271 − 199 =
16. 16.777 − 198 =
17. 17.255 − 198 =
18. 18.860 − 697 =
19. 19.741 − 458 =
20. 20.967 − 799 =
21. 21.333 − 198 =
22. 22.859 − 548 =
23. 23.868 − 667 =
24. 24.340 − 198 =
25. 25.899 − 698 =
26. 26.533 − 429 =
27. 27.967 − 697 =
28. 28.307 − 257 =
29. 29.797 − 598 =
30. 30.926 − 798 =
31. 31.688 − 178 =
32. 32.660 − 489 =
33. 33.740 − 399 =
34. 34.729 − 697 =
35. 35.784 − 599 =
36. 36.937 − 699 =
37. 37.636 − 588 =
38. 38.577 − 298 =
39. 39.145 − 127 =
40. 40.676 − 597 =

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