3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 600 · 40 questions

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

1. 1.955 − 589 =
2. 2.168 + 464 =
3. 3.619 + 409 =
4. 4.603 − 205 =
5. 5.945 − 391 =
6. 6.185 + 497 =
7. 7.791 − 519 =
8. 8.233 + 612 =
9. 9.779 − 585 =
10. 10.454 + 141 =
11. 11.867 − 151 =
12. 12.747 − 166 =
13. 13.911 − 604 =
14. 14.388 + 427 =
15. 15.476 − 312 =
16. 16.616 + 151 =
17. 17.490 − 216 =
18. 18.228 + 482 =
19. 19.473 + 115 =
20. 20.785 − 427 =
21. 21.816 − 226 =
22. 22.717 − 456 =
23. 23.647 − 242 =
24. 24.661 + 654 =
25. 25.691 + 498 =
26. 26.919 − 345 =
27. 27.952 − 211 =
28. 28.529 − 404 =
29. 29.276 + 241 =
30. 30.653 − 547 =
31. 31.375 + 352 =
32. 32.657 + 126 =
33. 33.795 − 239 =
34. 34.970 − 321 =
35. 35.326 + 376 =
36. 36.927 − 507 =
37. 37.249 + 311 =
38. 38.490 − 128 =
39. 39.472 + 482 =
40. 40.512 − 301 =

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