Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 633 · 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. 1.732 − 407 =
2. 2.509 − 489 =
3. 3.585 − 198 =
4. 4.443 − 169 =
5. 5.407 − 368 =
6. 6.789 − 697 =
7. 7.877 − 399 =
8. 8.748 − 278 =
9. 9.984 − 799 =
10. 10.957 − 567 =
11. 11.435 − 397 =
12. 12.813 − 587 =
13. 13.912 − 597 =
14. 14.532 − 298 =
15. 15.977 − 697 =
16. 16.942 − 648 =
17. 17.933 − 599 =
18. 18.566 − 297 =
19. 19.631 − 588 =
20. 20.979 − 499 =
21. 21.876 − 698 =
22. 22.999 − 677 =
23. 23.883 − 499 =
24. 24.835 − 488 =
25. 25.722 − 598 =
26. 26.728 − 509 =
27. 27.761 − 498 =
28. 28.955 − 799 =
29. 29.956 − 797 =
30. 30.259 − 128 =
31. 31.884 − 797 =
32. 32.544 − 287 =
33. 33.774 − 497 =
34. 34.982 − 398 =
35. 35.997 − 797 =
36. 36.421 − 268 =
37. 37.610 − 497 =
38. 38.735 − 299 =
39. 39.950 − 688 =
40. 40.301 − 199 =

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