Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 102 · 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. 1.402 − 299 =
2. 2.626 − 198 =
3. 3.901 − 797 =
4. 4.961 − 598 =
5. 5.769 − 598 =
6. 6.549 − 457 =
7. 7.813 − 598 =
8. 8.673 − 298 =
9. 9.358 − 299 =
10. 10.925 − 579 =
11. 11.750 − 199 =
12. 12.392 − 299 =
13. 13.664 − 187 =
14. 14.864 − 398 =
15. 15.931 − 388 =
16. 16.820 − 198 =
17. 17.886 − 699 =
18. 18.446 − 399 =
19. 19.874 − 299 =
20. 20.701 − 579 =
21. 21.496 − 398 =
22. 22.900 − 298 =
23. 23.519 − 497 =
24. 24.651 − 598 =
25. 25.510 − 398 =
26. 26.390 − 297 =
27. 27.824 − 169 =
28. 28.493 − 399 =
29. 29.540 − 198 =
30. 30.677 − 199 =
31. 31.366 − 199 =
32. 32.828 − 198 =
33. 33.996 − 419 =
34. 34.694 − 398 =
35. 35.717 − 697 =
36. 36.895 − 197 =
37. 37.982 − 557 =
38. 38.900 − 118 =
39. 39.714 − 497 =
40. 40.991 − 799 =

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