Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 392 · 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. 1.363 − 299 =
2. 2.449 − 199 =
3. 3.885 − 517 =
4. 4.774 − 219 =
5. 5.911 − 199 =
6. 6.623 − 399 =
7. 7.684 − 399 =
8. 8.979 − 498 =
9. 9.654 − 499 =
10. 10.875 − 298 =
11. 11.819 − 598 =
12. 12.560 − 398 =
13. 13.428 − 329 =
14. 14.688 − 478 =
15. 15.655 − 497 =
16. 16.461 − 399 =
17. 17.818 − 608 =
18. 18.811 − 538 =
19. 19.340 − 199 =
20. 20.666 − 599 =
21. 21.743 − 317 =
22. 22.835 − 398 =
23. 23.620 − 447 =
24. 24.998 − 578 =
25. 25.835 − 468 =
26. 26.817 − 459 =
27. 27.603 − 407 =
28. 28.603 − 297 =
29. 29.870 − 697 =
30. 30.550 − 299 =
31. 31.686 − 469 =
32. 32.842 − 698 =
33. 33.842 − 797 =
34. 34.671 − 597 =
35. 35.715 − 487 =
36. 36.818 − 699 =
37. 37.974 − 177 =
38. 38.837 − 148 =
39. 39.351 − 218 =
40. 40.882 − 668 =

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths