3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 120 · 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. 1.843 − 261 =
2. 2.185 + 247 =
3. 3.178 + 482 =
4. 4.446 − 187 =
5. 5.286 + 139 =
6. 6.786 − 224 =
7. 7.690 − 538 =
8. 8.563 − 137 =
9. 9.640 + 248 =
10. 10.544 − 185 =
11. 11.674 + 352 =
12. 12.845 − 215 =
13. 13.453 − 122 =
14. 14.294 + 389 =
15. 15.659 + 557 =
16. 16.336 + 211 =
17. 17.535 − 296 =
18. 18.800 − 644 =
19. 19.299 + 343 =
20. 20.338 + 179 =
21. 21.624 + 136 =
22. 22.326 + 614 =
23. 23.503 − 325 =
24. 24.656 − 142 =
25. 25.883 − 447 =
26. 26.520 + 663 =
27. 27.600 − 115 =
28. 28.591 + 359 =
29. 29.423 − 171 =
30. 30.371 + 222 =
31. 31.697 − 382 =
32. 32.865 − 508 =
33. 33.173 + 271 =
34. 34.739 + 137 =
35. 35.173 + 321 =
36. 36.660 − 426 =
37. 37.659 − 266 =
38. 38.477 − 149 =
39. 39.620 + 211 =
40. 40.286 + 181 =

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