Find the sum of numbers from 1 to 30 that are not divisible by 3.
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- First find the sum of all numbers from 1 to 30.
- Subtract three times the sum of the numbers from 1 to 10.
Show the answer and solution
Answer: 300
The sum of all numbers is 465. Multiples of 3 give 3 × (1 + … + 10) = 165. The difference is 300.