Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 970 · 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. 1.929 − 799 =
2. 2.717 − 698 =
3. 3.720 − 599 =
4. 4.923 − 797 =
5. 5.510 − 299 =
6. 6.615 − 169 =
7. 7.335 − 178 =
8. 8.592 − 229 =
9. 9.937 − 699 =
10. 10.690 − 229 =
11. 11.402 − 119 =
12. 12.335 − 299 =
13. 13.255 − 199 =
14. 14.895 − 799 =
15. 15.591 − 339 =
16. 16.815 − 219 =
17. 17.590 − 237 =
18. 18.950 − 199 =
19. 19.833 − 799 =
20. 20.729 − 407 =
21. 21.829 − 797 =
22. 22.606 − 398 =
23. 23.747 − 219 =
24. 24.873 − 538 =
25. 25.988 − 267 =
26. 26.759 − 549 =
27. 27.764 − 487 =
28. 28.599 − 197 =
29. 29.997 − 487 =
30. 30.829 − 697 =
31. 31.545 − 407 =
32. 32.846 − 667 =
33. 33.512 − 498 =
34. 34.968 − 498 =
35. 35.800 − 298 =
36. 36.683 − 598 =
37. 37.745 − 698 =
38. 38.580 − 399 =
39. 39.809 − 398 =
40. 40.453 − 399 =

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