3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 866 · 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. 1.783 + 306 =
2. 2.609 + 471 =
3. 3.647 − 427 =
4. 4.702 − 527 =
5. 5.641 − 159 =
6. 6.926 − 318 =
7. 7.728 − 231 =
8. 8.621 − 118 =
9. 9.879 − 655 =
10. 10.492 − 349 =
11. 11.341 + 142 =
12. 12.987 − 241 =
13. 13.279 + 414 =
14. 14.606 + 387 =
15. 15.485 − 122 =
16. 16.664 − 513 =
17. 17.556 − 408 =
18. 18.626 + 197 =
19. 19.489 + 181 =
20. 20.650 − 231 =
21. 21.571 − 359 =
22. 22.443 − 146 =
23. 23.573 + 565 =
24. 24.809 − 445 =
25. 25.480 + 301 =
26. 26.370 + 609 =
27. 27.466 − 259 =
28. 28.419 + 417 =
29. 29.227 + 298 =
30. 30.727 − 178 =
31. 31.487 + 294 =
32. 32.628 + 207 =
33. 33.362 + 268 =
34. 34.593 − 121 =
35. 35.314 + 513 =
36. 36.247 + 278 =
37. 37.535 + 173 =
38. 38.533 + 183 =
39. 39.649 − 146 =
40. 40.767 − 314 =

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