Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 326 · 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. 1.584 − 299 =
2. 2.972 − 239 =
3. 3.886 − 697 =
4. 4.859 − 198 =
5. 5.341 − 299 =
6. 6.578 − 419 =
7. 7.465 − 297 =
8. 8.494 − 399 =
9. 9.908 − 497 =
10. 10.533 − 118 =
11. 11.750 − 598 =
12. 12.338 − 197 =
13. 13.942 − 397 =
14. 14.503 − 458 =
15. 15.967 − 798 =
16. 16.822 − 398 =
17. 17.902 − 398 =
18. 18.812 − 429 =
19. 19.437 − 398 =
20. 20.975 − 699 =
21. 21.696 − 479 =
22. 22.901 − 278 =
23. 23.969 − 698 =
24. 24.483 − 418 =
25. 25.521 − 127 =
26. 26.628 − 399 =
27. 27.991 − 398 =
28. 28.867 − 699 =
29. 29.931 − 497 =
30. 30.984 − 647 =
31. 31.903 − 797 =
32. 32.448 − 128 =
33. 33.878 − 798 =
34. 34.990 − 298 =
35. 35.695 − 398 =
36. 36.664 − 589 =
37. 37.351 − 297 =
38. 38.785 − 697 =
39. 39.868 − 367 =
40. 40.710 − 598 =

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