Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 864 · 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. 1.764 − 499 =
2. 2.690 − 657 =
3. 3.601 − 199 =
4. 4.881 − 597 =
5. 5.352 − 198 =
6. 6.935 − 497 =
7. 7.806 − 198 =
8. 8.609 − 249 =
9. 9.970 − 669 =
10. 10.910 − 797 =
11. 11.563 − 297 =
12. 12.469 − 399 =
13. 13.719 − 118 =
14. 14.903 − 288 =
15. 15.853 − 199 =
16. 16.643 − 528 =
17. 17.518 − 319 =
18. 18.461 − 317 =
19. 19.844 − 799 =
20. 20.279 − 138 =
21. 21.798 − 697 =
22. 22.809 − 189 =
23. 23.310 − 267 =
24. 24.913 − 799 =
25. 25.990 − 459 =
26. 26.808 − 699 =
27. 27.700 − 498 =
28. 28.805 − 598 =
29. 29.622 − 499 =
30. 30.783 − 449 =
31. 31.514 − 278 =
32. 32.340 − 197 =
33. 33.527 − 377 =
34. 34.589 − 568 =
35. 35.548 − 289 =
36. 36.315 − 229 =
37. 37.499 − 458 =
38. 38.713 − 197 =
39. 39.877 − 599 =
40. 40.730 − 499 =

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