3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 682 · 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. 1.281 + 357 =
2. 2.898 − 201 =
3. 3.172 + 142 =
4. 4.431 − 217 =
5. 5.494 + 663 =
6. 6.542 − 112 =
7. 7.627 + 121 =
8. 8.746 + 256 =
9. 9.413 − 112 =
10. 10.838 − 607 =
11. 11.627 + 236 =
12. 12.629 + 122 =
13. 13.227 + 282 =
14. 14.196 + 467 =
15. 15.796 − 531 =
16. 16.181 + 364 =
17. 17.321 + 455 =
18. 18.307 + 551 =
19. 19.714 + 465 =
20. 20.576 + 175 =
21. 21.202 + 185 =
22. 22.680 + 449 =
23. 23.606 + 302 =
24. 24.676 + 553 =
25. 25.469 + 506 =
26. 26.935 − 294 =
27. 27.529 − 194 =
28. 28.596 − 141 =
29. 29.691 + 115 =
30. 30.569 + 404 =
31. 31.299 + 139 =
32. 32.571 − 224 =
33. 33.635 − 142 =
34. 34.322 + 246 =
35. 35.847 − 484 =
36. 36.206 + 368 =
37. 37.746 + 493 =
38. 38.837 − 275 =
39. 39.478 − 121 =
40. 40.932 − 469 =

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