Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 599 · 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. 1.493 − 199 =
2. 2.890 − 469 =
3. 3.932 − 647 =
4. 4.526 − 498 =
5. 5.980 − 627 =
6. 6.773 − 197 =
7. 7.814 − 697 =
8. 8.461 − 398 =
9. 9.985 − 227 =
10. 10.600 − 499 =
11. 11.985 − 437 =
12. 12.688 − 198 =
13. 13.465 − 298 =
14. 14.821 − 797 =
15. 15.912 − 567 =
16. 16.537 − 468 =
17. 17.858 − 597 =
18. 18.884 − 399 =
19. 19.881 − 598 =
20. 20.789 − 658 =
21. 21.508 − 399 =
22. 22.633 − 459 =
23. 23.962 − 799 =
24. 24.828 − 799 =
25. 25.820 − 447 =
26. 26.994 − 399 =
27. 27.713 − 598 =
28. 28.575 − 398 =
29. 29.407 − 147 =
30. 30.863 − 458 =
31. 31.315 − 199 =
32. 32.620 − 447 =
33. 33.901 − 498 =
34. 34.468 − 397 =
35. 35.683 − 489 =
36. 36.858 − 698 =
37. 37.798 − 259 =
38. 38.922 − 199 =
39. 39.786 − 288 =
40. 40.486 − 297 =

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