Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 980 · 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. 1.709 − 148 =
2. 2.846 − 628 =
3. 3.860 − 199 =
4. 4.684 − 299 =
5. 5.895 − 798 =
6. 6.366 − 297 =
7. 7.627 − 609 =
8. 8.700 − 639 =
9. 9.365 − 327 =
10. 10.512 − 197 =
11. 11.645 − 299 =
12. 12.788 − 298 =
13. 13.787 − 147 =
14. 14.793 − 347 =
15. 15.547 − 259 =
16. 16.963 − 699 =
17. 17.757 − 299 =
18. 18.999 − 697 =
19. 19.998 − 569 =
20. 20.787 − 499 =
21. 21.873 − 499 =
22. 22.850 − 199 =
23. 23.799 − 498 =
24. 24.310 − 218 =
25. 25.900 − 488 =
26. 26.815 − 499 =
27. 27.780 − 389 =
28. 28.943 − 599 =
29. 29.932 − 569 =
30. 30.941 − 599 =
31. 31.997 − 209 =
32. 32.921 − 597 =
33. 33.670 − 489 =
34. 34.787 − 249 =
35. 35.982 − 377 =
36. 36.285 − 199 =
37. 37.840 − 478 =
38. 38.675 − 617 =
39. 39.946 − 668 =
40. 40.938 − 598 =

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