Answer: 72874
Explanation:
To solve this, you can first find the sum of all numbers from 1 to 400. Using the formula for arithmetic series, you can get 1+2+3+4...+400=80200. Then, you can subtract all multiples of 11 from 1 to 400. That is 11+22+33+44+...+396. Dividing all numbers by 11, we have the new arithmetic series 1+2+3+4..+36, which using the formula, equals 666. Multiply this by 11 to get 7326 and subtract from 80200 to get 72874.