Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 562 · 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. 1.604 − 187 =
2. 2.361 − 199 =
3. 3.862 − 397 =
4. 4.723 − 197 =
5. 5.800 − 368 =
6. 6.606 − 397 =
7. 7.938 − 799 =
8. 8.683 − 299 =
9. 9.962 − 797 =
10. 10.638 − 219 =
11. 11.896 − 697 =
12. 12.773 − 367 =
13. 13.909 − 488 =
14. 14.856 − 199 =
15. 15.950 − 207 =
16. 16.489 − 367 =
17. 17.598 − 278 =
18. 18.755 − 699 =
19. 19.819 − 657 =
20. 20.724 − 189 =
21. 21.888 − 389 =
22. 22.875 − 517 =
23. 23.702 − 399 =
24. 24.735 − 699 =
25. 25.826 − 689 =
26. 26.707 − 129 =
27. 27.828 − 659 =
28. 28.915 − 137 =
29. 29.618 − 448 =
30. 30.556 − 397 =
31. 31.776 − 249 =
32. 32.888 − 667 =
33. 33.997 − 557 =
34. 34.877 − 318 =
35. 35.623 − 397 =
36. 36.894 − 499 =
37. 37.676 − 597 =
38. 38.508 − 338 =
39. 39.968 − 497 =
40. 40.284 − 197 =

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