Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 595 · 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. 1.793 − 697 =
2. 2.254 − 169 =
3. 3.414 − 197 =
4. 4.987 − 697 =
5. 5.989 − 799 =
6. 6.521 − 399 =
7. 7.531 − 428 =
8. 8.226 − 207 =
9. 9.821 − 499 =
10. 10.515 − 399 =
11. 11.804 − 597 =
12. 12.875 − 599 =
13. 13.424 − 398 =
14. 14.234 − 148 =
15. 15.461 − 207 =
16. 16.799 − 199 =
17. 17.561 − 489 =
18. 18.793 − 337 =
19. 19.656 − 597 =
20. 20.933 − 399 =
21. 21.761 − 217 =
22. 22.586 − 557 =
23. 23.661 − 499 =
24. 24.792 − 299 =
25. 25.686 − 299 =
26. 26.543 − 429 =
27. 27.793 − 299 =
28. 28.619 − 359 =
29. 29.962 − 658 =
30. 30.831 − 607 =
31. 31.692 − 318 =
32. 32.900 − 499 =
33. 33.948 − 498 =
34. 34.522 − 398 =
35. 35.695 − 298 =
36. 36.707 − 579 =
37. 37.500 − 327 =
38. 38.759 − 499 =
39. 39.629 − 497 =
40. 40.625 − 597 =

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