Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 814 · 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. 1.593 − 299 =
2. 2.660 − 159 =
3. 3.735 − 628 =
4. 4.233 − 127 =
5. 5.968 − 129 =
6. 6.953 − 339 =
7. 7.807 − 218 =
8. 8.990 − 198 =
9. 9.886 − 597 =
10. 10.393 − 299 =
11. 11.638 − 397 =
12. 12.821 − 797 =
13. 13.723 − 499 =
14. 14.900 − 498 =
15. 15.665 − 198 =
16. 16.976 − 697 =
17. 17.703 − 297 =
18. 18.604 − 299 =
19. 19.225 − 199 =
20. 20.873 − 367 =
21. 21.625 − 397 =
22. 22.627 − 179 =
23. 23.956 − 697 =
24. 24.872 − 399 =
25. 25.922 − 528 =
26. 26.754 − 498 =
27. 27.675 − 198 =
28. 28.744 − 698 =
29. 29.729 − 579 =
30. 30.989 − 117 =
31. 31.997 − 498 =
32. 32.795 − 278 =
33. 33.942 − 609 =
34. 34.949 − 167 =
35. 35.644 − 199 =
36. 36.757 − 499 =
37. 37.851 − 148 =
38. 38.707 − 638 =
39. 39.583 − 519 =
40. 40.420 − 289 =

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