3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 401 · 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. 1.486 + 265 =
2. 2.629 + 603 =
3. 3.531 − 187 =
4. 4.766 − 463 =
5. 5.725 + 491 =
6. 6.654 + 459 =
7. 7.436 − 249 =
8. 8.661 + 591 =
9. 9.313 + 186 =
10. 10.542 + 456 =
11. 11.271 + 599 =
12. 12.728 − 183 =
13. 13.713 − 389 =
14. 14.654 − 128 =
15. 15.201 + 453 =
16. 16.532 − 397 =
17. 17.784 − 161 =
18. 18.522 − 338 =
19. 19.547 + 579 =
20. 20.483 − 143 =
21. 21.854 − 568 =
22. 22.773 + 172 =
23. 23.787 − 196 =
24. 24.629 − 121 =
25. 25.584 − 378 =
26. 26.672 + 621 =
27. 27.701 − 288 =
28. 28.758 + 499 =
29. 29.279 + 375 =
30. 30.454 − 294 =
31. 31.419 + 439 =
32. 32.873 − 274 =
33. 33.677 + 385 =
34. 34.974 − 541 =
35. 35.894 − 213 =
36. 36.340 + 317 =
37. 37.230 + 314 =
38. 38.466 − 321 =
39. 39.705 − 394 =
40. 40.447 + 626 =

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