Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 951 · 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. 1.542 − 397 =
2. 2.664 − 609 =
3. 3.550 − 399 =
4. 4.634 − 599 =
5. 5.713 − 658 =
6. 6.722 − 539 =
7. 7.947 − 609 =
8. 8.810 − 599 =
9. 9.865 − 677 =
10. 10.443 − 398 =
11. 11.790 − 299 =
12. 12.514 − 199 =
13. 13.935 − 179 =
14. 14.774 − 598 =
15. 15.695 − 318 =
16. 16.577 − 449 =
17. 17.563 − 299 =
18. 18.912 − 489 =
19. 19.276 − 139 =
20. 20.744 − 567 =
21. 21.595 − 497 =
22. 22.924 − 568 =
23. 23.879 − 799 =
24. 24.716 − 599 =
25. 25.822 − 298 =
26. 26.790 − 599 =
27. 27.334 − 207 =
28. 28.469 − 269 =
29. 29.521 − 398 =
30. 30.595 − 567 =
31. 31.453 − 329 =
32. 32.938 − 398 =
33. 33.749 − 498 =
34. 34.541 − 408 =
35. 35.820 − 799 =
36. 36.968 − 798 =
37. 37.842 − 397 =
38. 38.750 − 378 =
39. 39.634 − 597 =
40. 40.623 − 389 =

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