Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 134 · 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. 1.803 − 299 =
2. 2.791 − 399 =
3. 3.544 − 427 =
4. 4.568 − 398 =
5. 5.595 − 539 =
6. 6.767 − 697 =
7. 7.740 − 699 =
8. 8.240 − 207 =
9. 9.877 − 597 =
10. 10.816 − 799 =
11. 11.732 − 199 =
12. 12.939 − 498 =
13. 13.909 − 269 =
14. 14.769 − 298 =
15. 15.464 − 397 =
16. 16.529 − 197 =
17. 17.493 − 338 =
18. 18.609 − 397 =
19. 19.665 − 199 =
20. 20.533 − 499 =
21. 21.903 − 628 =
22. 22.452 − 318 =
23. 23.566 − 197 =
24. 24.679 − 638 =
25. 25.438 − 297 =
26. 26.944 − 498 =
27. 27.895 − 797 =
28. 28.373 − 319 =
29. 29.922 − 399 =
30. 30.998 − 568 =
31. 31.840 − 598 =
32. 32.241 − 197 =
33. 33.974 − 597 =
34. 34.722 − 318 =
35. 35.718 − 339 =
36. 36.701 − 439 =
37. 37.609 − 308 =
38. 38.970 − 697 =
39. 39.980 − 358 =
40. 40.714 − 198 =

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