Explanation:
According to this description we need a number that can be divided by 2,3 and 4 since the amount of rocks can be described by a natural number. However if a number is divided by 4 it is divided by 2 as well since 2*2=4.
![(x)/(4) = \alpha \\ (x)/(2) = 2 \alpha](https://img.qammunity.org/2020/formulas/mathematics/college/9hfrw96wn285i4rvu5wq4tc65b07ow4qe3.png)
If α is a natural number then 2*α is a natural number as well as the product of two natural numbers.
Which means that we need a number devided by 3 and 4.
The smallest number that fulfills this demand is 3*4=12.
Also any product of 12 with any natural number can be devided by 3, 4 and 2.
If the exercise asks for the numbers that are divided only by 2,3 and 4 these are:
![{3}^( \alpha ) * 12 \: and \: {4}^( \alpha ) * 12 \: \\ where \: \alpha \: belongs \: to \: the \: set \: of \: all \: </p><p>\\ natural \: numbers](https://img.qammunity.org/2020/formulas/mathematics/college/ebksrjkr4wqnsfttijg8vslw1h9vsqg6gp.png)