Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 132 · 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. 1.787 − 199 =
2. 2.746 − 699 =
3. 3.676 − 129 =
4. 4.271 − 208 =
5. 5.760 − 648 =
6. 6.780 − 187 =
7. 7.797 − 578 =
8. 8.813 − 597 =
9. 9.581 − 297 =
10. 10.917 − 399 =
11. 11.653 − 578 =
12. 12.999 − 599 =
13. 13.683 − 598 =
14. 14.853 − 279 =
15. 15.797 − 238 =
16. 16.796 − 598 =
17. 17.891 − 599 =
18. 18.722 − 507 =
19. 19.780 − 199 =
20. 20.788 − 637 =
21. 21.521 − 247 =
22. 22.658 − 397 =
23. 23.863 − 517 =
24. 24.328 − 199 =
25. 25.887 − 499 =
26. 26.969 − 799 =
27. 27.984 − 699 =
28. 28.853 − 599 =
29. 29.569 − 199 =
30. 30.478 − 397 =
31. 31.495 − 297 =
32. 32.675 − 659 =
33. 33.562 − 138 =
34. 34.635 − 399 =
35. 35.807 − 659 =
36. 36.828 − 669 =
37. 37.291 − 199 =
38. 38.914 − 298 =
39. 39.752 − 698 =
40. 40.633 − 497 =

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