Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 205 · 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. 1.727 − 697 =
2. 2.698 − 138 =
3. 3.774 − 397 =
4. 4.352 − 198 =
5. 5.575 − 478 =
6. 6.855 − 199 =
7. 7.312 − 297 =
8. 8.658 − 397 =
9. 9.411 − 269 =
10. 10.515 − 368 =
11. 11.870 − 197 =
12. 12.781 − 339 =
13. 13.647 − 299 =
14. 14.802 − 197 =
15. 15.903 − 698 =
16. 16.515 − 498 =
17. 17.780 − 299 =
18. 18.686 − 497 =
19. 19.735 − 678 =
20. 20.764 − 358 =
21. 21.840 − 238 =
22. 22.954 − 797 =
23. 23.843 − 519 =
24. 24.213 − 169 =
25. 25.756 − 399 =
26. 26.820 − 497 =
27. 27.924 − 587 =
28. 28.434 − 297 =
29. 29.585 − 299 =
30. 30.537 − 269 =
31. 31.484 − 269 =
32. 32.859 − 499 =
33. 33.863 − 417 =
34. 34.736 − 499 =
35. 35.379 − 288 =
36. 36.548 − 248 =
37. 37.736 − 637 =
38. 38.887 − 197 =
39. 39.415 − 398 =
40. 40.950 − 399 =

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