3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 770 · 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. 1.899 − 312 =
2. 2.156 + 273 =
3. 3.734 − 169 =
4. 4.422 − 153 =
5. 5.579 + 451 =
6. 6.746 − 538 =
7. 7.302 + 613 =
8. 8.377 + 512 =
9. 9.523 + 173 =
10. 10.448 + 161 =
11. 11.746 + 471 =
12. 12.945 − 534 =
13. 13.470 + 234 =
14. 14.478 − 233 =
15. 15.461 + 368 =
16. 16.162 + 236 =
17. 17.877 − 751 =
18. 18.361 + 547 =
19. 19.847 − 592 =
20. 20.560 + 229 =
21. 21.218 + 403 =
22. 22.881 − 585 =
23. 23.357 + 395 =
24. 24.573 + 513 =
25. 25.539 − 222 =
26. 26.748 − 531 =
27. 27.285 + 136 =
28. 28.485 − 365 =
29. 29.335 + 123 =
30. 30.430 − 257 =
31. 31.702 − 357 =
32. 32.697 − 171 =
33. 33.572 + 129 =
34. 34.572 − 424 =
35. 35.611 − 256 =
36. 36.221 + 249 =
37. 37.518 − 163 =
38. 38.481 − 154 =
39. 39.495 − 122 =
40. 40.960 − 145 =

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