Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 610 · 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. 1.743 − 599 =
2. 2.709 − 497 =
3. 3.859 − 598 =
4. 4.638 − 299 =
5. 5.625 − 588 =
6. 6.696 − 597 =
7. 7.683 − 527 =
8. 8.326 − 298 =
9. 9.936 − 697 =
10. 10.703 − 418 =
11. 11.851 − 607 =
12. 12.763 − 698 =
13. 13.746 − 699 =
14. 14.967 − 199 =
15. 15.990 − 797 =
16. 16.392 − 198 =
17. 17.460 − 197 =
18. 18.381 − 269 =
19. 19.912 − 299 =
20. 20.990 − 228 =
21. 21.648 − 499 =
22. 22.738 − 668 =
23. 23.992 − 799 =
24. 24.900 − 649 =
25. 25.540 − 399 =
26. 26.735 − 458 =
27. 27.928 − 257 =
28. 28.986 − 799 =
29. 29.314 − 279 =
30. 30.433 − 148 =
31. 31.984 − 279 =
32. 32.391 − 169 =
33. 33.409 − 179 =
34. 34.882 − 608 =
35. 35.854 − 298 =
36. 36.947 − 798 =
37. 37.730 − 499 =
38. 38.507 − 297 =
39. 39.371 − 189 =
40. 40.895 − 198 =

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