Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 116 · 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. 1.442 − 419 =
2. 2.368 − 299 =
3. 3.824 − 599 =
4. 4.216 − 149 =
5. 5.526 − 299 =
6. 6.731 − 599 =
7. 7.754 − 257 =
8. 8.971 − 698 =
9. 9.859 − 289 =
10. 10.959 − 139 =
11. 11.834 − 799 =
12. 12.665 − 579 =
13. 13.404 − 297 =
14. 14.716 − 639 =
15. 15.558 − 319 =
16. 16.837 − 447 =
17. 17.808 − 698 =
18. 18.948 − 697 =
19. 19.954 − 597 =
20. 20.955 − 797 =
21. 21.822 − 688 =
22. 22.847 − 428 =
23. 23.817 − 137 =
24. 24.556 − 498 =
25. 25.562 − 498 =
26. 26.969 − 428 =
27. 27.354 − 198 =
28. 28.412 − 199 =
29. 29.816 − 499 =
30. 30.538 − 197 =
31. 31.832 − 397 =
32. 32.540 − 137 =
33. 33.789 − 698 =
34. 34.531 − 368 =
35. 35.700 − 657 =
36. 36.796 − 438 =
37. 37.744 − 498 =
38. 38.760 − 199 =
39. 39.974 − 678 =
40. 40.706 − 679 =

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