Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 824 · 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. 1.611 − 397 =
2. 2.831 − 797 =
3. 3.858 − 428 =
4. 4.785 − 299 =
5. 5.796 − 437 =
6. 6.750 − 118 =
7. 7.978 − 198 =
8. 8.647 − 397 =
9. 9.545 − 498 =
10. 10.915 − 158 =
11. 11.984 − 319 =
12. 12.743 − 558 =
13. 13.780 − 628 =
14. 14.940 − 149 =
15. 15.921 − 699 =
16. 16.897 − 687 =
17. 17.368 − 199 =
18. 18.854 − 197 =
19. 19.881 − 798 =
20. 20.853 − 639 =
21. 21.691 − 247 =
22. 22.679 − 598 =
23. 23.808 − 687 =
24. 24.596 − 559 =
25. 25.852 − 467 =
26. 26.836 − 798 =
27. 27.832 − 499 =
28. 28.271 − 127 =
29. 29.949 − 398 =
30. 30.551 − 148 =
31. 31.951 − 598 =
32. 32.927 − 589 =
33. 33.845 − 197 =
34. 34.631 − 399 =
35. 35.889 − 617 =
36. 36.497 − 298 =
37. 37.997 − 799 =
38. 38.787 − 397 =
39. 39.488 − 399 =
40. 40.999 − 558 =

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