3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 507 · 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. 1.359 + 626 =
2. 2.454 − 176 =
3. 3.723 + 258 =
4. 4.707 − 245 =
5. 5.509 − 221 =
6. 6.208 + 231 =
7. 7.924 − 137 =
8. 8.827 − 201 =
9. 9.909 − 238 =
10. 10.533 + 518 =
11. 11.370 + 321 =
12. 12.847 − 644 =
13. 13.560 − 261 =
14. 14.513 + 391 =
15. 15.231 + 488 =
16. 16.685 + 154 =
17. 17.741 − 145 =
18. 18.436 − 336 =
19. 19.868 − 356 =
20. 20.866 − 293 =
21. 21.711 − 405 =
22. 22.831 − 169 =
23. 23.220 + 665 =
24. 24.262 + 467 =
25. 25.781 + 206 =
26. 26.166 + 618 =
27. 27.784 + 307 =
28. 28.855 − 261 =
29. 29.574 + 241 =
30. 30.626 − 201 =
31. 31.135 + 546 =
32. 32.611 + 617 =
33. 33.567 − 133 =
34. 34.534 − 274 =
35. 35.656 + 381 =
36. 36.390 + 408 =
37. 37.694 + 486 =
38. 38.567 − 213 =
39. 39.806 − 423 =
40. 40.856 − 394 =

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