Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 773 · 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. 1.920 − 797 =
2. 2.951 − 398 =
3. 3.731 − 398 =
4. 4.577 − 189 =
5. 5.336 − 218 =
6. 6.772 − 197 =
7. 7.863 − 799 =
8. 8.739 − 597 =
9. 9.865 − 698 =
10. 10.440 − 198 =
11. 11.352 − 298 =
12. 12.716 − 188 =
13. 13.853 − 797 =
14. 14.468 − 399 =
15. 15.763 − 609 =
16. 16.738 − 499 =
17. 17.743 − 688 =
18. 18.988 − 698 =
19. 19.384 − 198 =
20. 20.905 − 219 =
21. 21.812 − 197 =
22. 22.988 − 799 =
23. 23.984 − 659 =
24. 24.713 − 499 =
25. 25.764 − 698 =
26. 26.611 − 398 =
27. 27.874 − 118 =
28. 28.701 − 407 =
29. 29.667 − 607 =
30. 30.876 − 297 =
31. 31.932 − 399 =
32. 32.925 − 398 =
33. 33.988 − 697 =
34. 34.294 − 257 =
35. 35.860 − 497 =
36. 36.338 − 317 =
37. 37.728 − 379 =
38. 38.693 − 589 =
39. 39.917 − 149 =
40. 40.792 − 499 =

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