Using all the numbers from 1 to 9 and without repeating any, find three numbers of three figures each such that the second is double the first and the third is triple the first.

**What number is it?**

#### Solution

**The numbers are 219, 438 and 657.**

The result is obtained by scoring taking into account that the five can only go in the second position of the third number, since its double is ten and it is not possible to place zeros, it is not double any integer nor can it be triple because five would be repeated. We must also keep in mind that 2, 4, 6 are the only digits such that the second is double the first and the third is triple the first. These are placed as the most significant digit of the three numbers to form.