Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 451 · 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. 1.385 − 169 =
2. 2.802 − 697 =
3. 3.702 − 199 =
4. 4.965 − 197 =
5. 5.776 − 559 =
6. 6.989 − 798 =
7. 7.542 − 329 =
8. 8.380 − 338 =
9. 9.678 − 597 =
10. 10.977 − 799 =
11. 11.848 − 599 =
12. 12.696 − 649 =
13. 13.403 − 198 =
14. 14.751 − 597 =
15. 15.908 − 189 =
16. 16.606 − 199 =
17. 17.601 − 238 =
18. 18.477 − 299 =
19. 19.586 − 369 =
20. 20.586 − 417 =
21. 21.877 − 548 =
22. 22.519 − 158 =
23. 23.719 − 597 =
24. 24.741 − 257 =
25. 25.936 − 668 =
26. 26.901 − 798 =
27. 27.886 − 487 =
28. 28.481 − 129 =
29. 29.695 − 499 =
30. 30.691 − 488 =
31. 31.821 − 399 =
32. 32.440 − 368 =
33. 33.331 − 278 =
34. 34.919 − 798 =
35. 35.862 − 197 =
36. 36.414 − 198 =
37. 37.999 − 698 =
38. 38.603 − 307 =
39. 39.696 − 499 =
40. 40.341 − 289 =

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