Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 456 · 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. 1.360 − 298 =
2. 2.473 − 127 =
3. 3.851 − 297 =
4. 4.888 − 697 =
5. 5.939 − 199 =
6. 6.494 − 257 =
7. 7.510 − 227 =
8. 8.661 − 297 =
9. 9.852 − 148 =
10. 10.704 − 297 =
11. 11.760 − 559 =
12. 12.900 − 698 =
13. 13.615 − 399 =
14. 14.794 − 699 =
15. 15.553 − 399 =
16. 16.541 − 199 =
17. 17.982 − 799 =
18. 18.943 − 339 =
19. 19.903 − 267 =
20. 20.831 − 798 =
21. 21.820 − 377 =
22. 22.893 − 799 =
23. 23.828 − 399 =
24. 24.752 − 129 =
25. 25.477 − 299 =
26. 26.787 − 197 =
27. 27.422 − 297 =
28. 28.419 − 199 =
29. 29.405 − 249 =
30. 30.820 − 567 =
31. 31.682 − 578 =
32. 32.593 − 499 =
33. 33.300 − 197 =
34. 34.621 − 499 =
35. 35.676 − 398 =
36. 36.522 − 397 =
37. 37.513 − 199 =
38. 38.545 − 199 =
39. 39.997 − 619 =
40. 40.864 − 297 =

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