Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 839 · 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. 1.458 − 247 =
2. 2.985 − 199 =
3. 3.550 − 527 =
4. 4.995 − 497 =
5. 5.776 − 678 =
6. 6.833 − 797 =
7. 7.913 − 198 =
8. 8.573 − 339 =
9. 9.465 − 329 =
10. 10.767 − 398 =
11. 11.770 − 699 =
12. 12.781 − 697 =
13. 13.919 − 149 =
14. 14.490 − 298 =
15. 15.869 − 397 =
16. 16.455 − 439 =
17. 17.774 − 597 =
18. 18.588 − 489 =
19. 19.963 − 687 =
20. 20.633 − 118 =
21. 21.902 − 297 =
22. 22.734 − 208 =
23. 23.882 − 399 =
24. 24.677 − 298 =
25. 25.877 − 798 =
26. 26.438 − 399 =
27. 27.900 − 799 =
28. 28.685 − 297 =
29. 29.532 − 299 =
30. 30.600 − 548 =
31. 31.723 − 617 =
32. 32.950 − 399 =
33. 33.639 − 499 =
34. 34.395 − 377 =
35. 35.470 − 357 =
36. 36.999 − 119 =
37. 37.451 − 299 =
38. 38.844 − 398 =
39. 39.981 − 697 =
40. 40.923 − 497 =

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