Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 143 · 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. 1.545 − 297 =
2. 2.781 − 649 =
3. 3.419 − 397 =
4. 4.834 − 267 =
5. 5.861 − 669 =
6. 6.918 − 197 =
7. 7.616 − 578 =
8. 8.372 − 199 =
9. 9.862 − 299 =
10. 10.764 − 489 =
11. 11.330 − 299 =
12. 12.986 − 427 =
13. 13.401 − 297 =
14. 14.746 − 678 =
15. 15.353 − 247 =
16. 16.423 − 228 =
17. 17.536 − 298 =
18. 18.334 − 299 =
19. 19.667 − 417 =
20. 20.856 − 799 =
21. 21.640 − 597 =
22. 22.969 − 317 =
23. 23.402 − 329 =
24. 24.946 − 657 =
25. 25.866 − 239 =
26. 26.640 − 538 =
27. 27.564 − 198 =
28. 28.349 − 279 =
29. 29.924 − 799 =
30. 30.892 − 668 =
31. 31.759 − 597 =
32. 32.915 − 377 =
33. 33.705 − 657 =
34. 34.983 − 199 =
35. 35.606 − 197 =
36. 36.593 − 197 =
37. 37.669 − 578 =
38. 38.836 − 799 =
39. 39.980 − 639 =
40. 40.885 − 497 =

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