Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 19 · 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. 1.467 − 268 =
2. 2.583 − 408 =
3. 3.975 − 668 =
4. 4.858 − 637 =
5. 5.629 − 247 =
6. 6.237 − 198 =
7. 7.786 − 598 =
8. 8.496 − 399 =
9. 9.949 − 309 =
10. 10.826 − 798 =
11. 11.545 − 518 =
12. 12.565 − 499 =
13. 13.433 − 419 =
14. 14.852 − 797 =
15. 15.720 − 228 =
16. 16.469 − 258 =
17. 17.491 − 397 =
18. 18.717 − 687 =
19. 19.773 − 697 =
20. 20.956 − 799 =
21. 21.824 − 149 =
22. 22.435 − 308 =
23. 23.575 − 298 =
24. 24.948 − 648 =
25. 25.996 − 798 =
26. 26.862 − 198 =
27. 27.898 − 569 =
28. 28.695 − 658 =
29. 29.939 − 799 =
30. 30.715 − 349 =
31. 31.793 − 127 =
32. 32.589 − 399 =
33. 33.725 − 537 =
34. 34.936 − 697 =
35. 35.601 − 318 =
36. 36.662 − 499 =
37. 37.526 − 479 =
38. 38.886 − 247 =
39. 39.931 − 797 =
40. 40.792 − 397 =

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