Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 525 · 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. 1.298 − 197 =
2. 2.914 − 599 =
3. 3.942 − 167 =
4. 4.678 − 578 =
5. 5.894 − 797 =
6. 6.866 − 798 =
7. 7.513 − 367 =
8. 8.956 − 549 =
9. 9.538 − 438 =
10. 10.942 − 638 =
11. 11.727 − 159 =
12. 12.899 − 798 =
13. 13.601 − 498 =
14. 14.449 − 358 =
15. 15.855 − 799 =
16. 16.799 − 699 =
17. 17.822 − 449 =
18. 18.840 − 307 =
19. 19.857 − 498 =
20. 20.812 − 298 =
21. 21.522 − 397 =
22. 22.945 − 397 =
23. 23.905 − 498 =
24. 24.987 − 797 =
25. 25.747 − 697 =
26. 26.847 − 399 =
27. 27.878 − 599 =
28. 28.713 − 278 =
29. 29.894 − 298 =
30. 30.972 − 799 =
31. 31.683 − 589 =
32. 32.726 − 349 =
33. 33.814 − 188 =
34. 34.358 − 257 =
35. 35.578 − 198 =
36. 36.370 − 247 =
37. 37.628 − 169 =
38. 38.999 − 259 =
39. 39.802 − 397 =
40. 40.784 − 598 =

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