Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 42 · 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. 1.494 − 298 =
2. 2.850 − 378 =
3. 3.613 − 297 =
4. 4.665 − 499 =
5. 5.801 − 397 =
6. 6.757 − 599 =
7. 7.651 − 629 =
8. 8.761 − 598 =
9. 9.939 − 598 =
10. 10.737 − 497 =
11. 11.859 − 598 =
12. 12.473 − 319 =
13. 13.908 − 797 =
14. 14.565 − 498 =
15. 15.834 − 599 =
16. 16.900 − 698 =
17. 17.481 − 298 =
18. 18.778 − 299 =
19. 19.861 − 299 =
20. 20.597 − 238 =
21. 21.478 − 267 =
22. 22.800 − 277 =
23. 23.706 − 567 =
24. 24.735 − 598 =
25. 25.648 − 128 =
26. 26.635 − 419 =
27. 27.991 − 497 =
28. 28.765 − 679 =
29. 29.665 − 397 =
30. 30.467 − 299 =
31. 31.910 − 798 =
32. 32.271 − 198 =
33. 33.616 − 158 =
34. 34.570 − 298 =
35. 35.426 − 198 =
36. 36.715 − 298 =
37. 37.326 − 239 =
38. 38.561 − 199 =
39. 39.646 − 597 =
40. 40.598 − 199 =

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