Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 498 · 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. 1.634 − 539 =
2. 2.747 − 629 =
3. 3.844 − 548 =
4. 4.821 − 597 =
5. 5.650 − 298 =
6. 6.871 − 797 =
7. 7.336 − 219 =
8. 8.901 − 538 =
9. 9.801 − 299 =
10. 10.318 − 197 =
11. 11.333 − 197 =
12. 12.428 − 398 =
13. 13.748 − 247 =
14. 14.353 − 257 =
15. 15.723 − 429 =
16. 16.398 − 249 =
17. 17.497 − 288 =
18. 18.780 − 299 =
19. 19.797 − 298 =
20. 20.658 − 378 =
21. 21.446 − 398 =
22. 22.223 − 199 =
23. 23.999 − 297 =
24. 24.843 − 799 =
25. 25.990 − 699 =
26. 26.403 − 298 =
27. 27.860 − 589 =
28. 28.618 − 538 =
29. 29.913 − 269 =
30. 30.757 − 417 =
31. 31.899 − 199 =
32. 32.811 − 429 =
33. 33.758 − 399 =
34. 34.804 − 699 =
35. 35.526 − 348 =
36. 36.837 − 799 =
37. 37.658 − 479 =
38. 38.279 − 208 =
39. 39.416 − 379 =
40. 40.596 − 229 =

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