Henry Ernest Dudeney/Modern Puzzles/68 - Threes and Sevens/Solution

by : $68$

 * Threes and Sevens

Solution
offers up $3,333,377,733$.

This is divisible by $3$ and $7$, and the sum of its digits is $42$, also divisible by $3$ and $7$.

In his words:
 * There must be at fewest three $7$'s and seven $3$'s, and the $7$'s must be placed as far to the right as possible.

However, we also offer up $777$ which equally well fulfils the conditions of the question.