Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 997 · 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. 1.740 − 199 =
2. 2.479 − 379 =
3. 3.779 − 599 =
4. 4.879 − 497 =
5. 5.488 − 438 =
6. 6.534 − 139 =
7. 7.884 − 499 =
8. 8.604 − 398 =
9. 9.606 − 557 =
10. 10.853 − 399 =
11. 11.701 − 438 =
12. 12.460 − 369 =
13. 13.986 − 399 =
14. 14.764 − 499 =
15. 15.801 − 609 =
16. 16.783 − 197 =
17. 17.264 − 117 =
18. 18.932 − 798 =
19. 19.814 − 298 =
20. 20.905 − 599 =
21. 21.587 − 497 =
22. 22.364 − 299 =
23. 23.935 − 799 =
24. 24.681 − 389 =
25. 25.427 − 298 =
26. 26.372 − 358 =
27. 27.765 − 599 =
28. 28.909 − 397 =
29. 29.723 − 158 =
30. 30.890 − 599 =
31. 31.904 − 798 =
32. 32.355 − 279 =
33. 33.865 − 797 =
34. 34.635 − 397 =
35. 35.529 − 199 =
36. 36.637 − 538 =
37. 37.737 − 639 =
38. 38.732 − 399 =
39. 39.819 − 697 =
40. 40.572 − 519 =

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