Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 632 · 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. 1.922 − 599 =
2. 2.572 − 359 =
3. 3.939 − 308 =
4. 4.835 − 498 =
5. 5.673 − 648 =
6. 6.422 − 397 =
7. 7.640 − 227 =
8. 8.731 − 559 =
9. 9.479 − 299 =
10. 10.965 − 169 =
11. 11.300 − 198 =
12. 12.732 − 149 =
13. 13.793 − 699 =
14. 14.460 − 199 =
15. 15.942 − 797 =
16. 16.438 − 259 =
17. 17.365 − 199 =
18. 18.276 − 248 =
19. 19.716 − 319 =
20. 20.983 − 798 =
21. 21.448 − 398 =
22. 22.750 − 649 =
23. 23.917 − 299 =
24. 24.266 − 197 =
25. 25.501 − 399 =
26. 26.579 − 198 =
27. 27.519 − 277 =
28. 28.594 − 399 =
29. 29.424 − 398 =
30. 30.872 − 797 =
31. 31.345 − 297 =
32. 32.564 − 489 =
33. 33.828 − 198 =
34. 34.519 − 299 =
35. 35.805 − 137 =
36. 36.688 − 447 =
37. 37.746 − 697 =
38. 38.629 − 599 =
39. 39.970 − 799 =
40. 40.842 − 198 =

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