3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 390 · 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. 1.547 − 306 =
2. 2.444 − 193 =
3. 3.751 + 327 =
4. 4.584 − 176 =
5. 5.474 − 359 =
6. 6.507 + 418 =
7. 7.782 − 565 =
8. 8.515 + 157 =
9. 9.650 − 119 =
10. 10.554 + 562 =
11. 11.677 + 119 =
12. 12.912 − 281 =
13. 13.529 − 321 =
14. 14.524 − 326 =
15. 15.414 − 171 =
16. 16.969 − 236 =
17. 17.462 − 316 =
18. 18.716 + 397 =
19. 19.361 + 187 =
20. 20.876 − 314 =
21. 21.976 − 849 =
22. 22.278 + 342 =
23. 23.696 + 323 =
24. 24.419 − 215 =
25. 25.230 + 168 =
26. 26.687 − 465 =
27. 27.778 + 681 =
28. 28.428 − 306 =
29. 29.747 + 591 =
30. 30.133 + 221 =
31. 31.670 + 643 =
32. 32.661 − 252 =
33. 33.833 − 155 =
34. 34.228 + 351 =
35. 35.153 + 337 =
36. 36.983 − 175 =
37. 37.966 − 258 =
38. 38.312 + 359 =
39. 39.591 + 163 =
40. 40.713 − 143 =

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