Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 979 · 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. 1.503 − 439 =
2. 2.621 − 297 =
3. 3.623 − 419 =
4. 4.455 − 297 =
5. 5.673 − 577 =
6. 6.847 − 598 =
7. 7.809 − 699 =
8. 8.844 − 297 =
9. 9.812 − 689 =
10. 10.675 − 298 =
11. 11.353 − 298 =
12. 12.225 − 197 =
13. 13.530 − 387 =
14. 14.711 − 538 =
15. 15.372 − 198 =
16. 16.685 − 658 =
17. 17.665 − 619 =
18. 18.897 − 799 =
19. 19.742 − 657 =
20. 20.815 − 697 =
21. 21.826 − 607 =
22. 22.381 − 199 =
23. 23.717 − 397 =
24. 24.192 − 148 =
25. 25.952 − 797 =
26. 26.905 − 517 =
27. 27.425 − 298 =
28. 28.786 − 128 =
29. 29.678 − 488 =
30. 30.684 − 329 =
31. 31.455 − 198 =
32. 32.493 − 269 =
33. 33.979 − 797 =
34. 34.735 − 399 =
35. 35.952 − 148 =
36. 36.666 − 288 =
37. 37.902 − 269 =
38. 38.709 − 619 =
39. 39.857 − 499 =
40. 40.978 − 699 =

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