Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 931 · 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. 1.826 − 797 =
2. 2.707 − 578 =
3. 3.924 − 299 =
4. 4.542 − 417 =
5. 5.990 − 628 =
6. 6.606 − 399 =
7. 7.920 − 188 =
8. 8.914 − 697 =
9. 9.343 − 299 =
10. 10.644 − 507 =
11. 11.643 − 507 =
12. 12.845 − 579 =
13. 13.871 − 797 =
14. 14.792 − 298 =
15. 15.919 − 597 =
16. 16.390 − 297 =
17. 17.597 − 279 =
18. 18.203 − 137 =
19. 19.849 − 598 =
20. 20.946 − 278 =
21. 21.697 − 639 =
22. 22.529 − 269 =
23. 23.672 − 619 =
24. 24.656 − 498 =
25. 25.891 − 697 =
26. 26.393 − 298 =
27. 27.689 − 299 =
28. 28.638 − 297 =
29. 29.676 − 397 =
30. 30.734 − 419 =
31. 31.930 − 299 =
32. 32.631 − 599 =
33. 33.935 − 797 =
34. 34.747 − 599 =
35. 35.932 − 699 =
36. 36.901 − 698 =
37. 37.669 − 598 =
38. 38.870 − 628 =
39. 39.856 − 599 =
40. 40.642 − 599 =

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