Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 911 · 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. 1.878 − 607 =
2. 2.911 − 209 =
3. 3.874 − 477 =
4. 4.645 − 198 =
5. 5.898 − 697 =
6. 6.709 − 499 =
7. 7.718 − 698 =
8. 8.623 − 297 =
9. 9.707 − 218 =
10. 10.936 − 498 =
11. 11.910 − 627 =
12. 12.384 − 199 =
13. 13.961 − 349 =
14. 14.849 − 499 =
15. 15.902 − 797 =
16. 16.948 − 799 =
17. 17.997 − 798 =
18. 18.371 − 297 =
19. 19.458 − 339 =
20. 20.798 − 497 =
21. 21.802 − 598 =
22. 22.166 − 147 =
23. 23.881 − 207 =
24. 24.570 − 478 =
25. 25.739 − 397 =
26. 26.473 − 197 =
27. 27.729 − 199 =
28. 28.929 − 799 =
29. 29.842 − 697 =
30. 30.918 − 478 =
31. 31.749 − 297 =
32. 32.643 − 278 =
33. 33.691 − 599 =
34. 34.811 − 258 =
35. 35.954 − 299 =
36. 36.720 − 548 =
37. 37.309 − 118 =
38. 38.611 − 567 =
39. 39.223 − 188 =
40. 40.544 − 158 =

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