Another example is to calculate the regulatory information of viruses. If a virus has 10 protein coding genes and all the genes express one by one in sequence and only express once, how much should be the regulatory information? The probability for each gene expression is the same, so the formula I=log(N) can be used. For the first gene to express, you have 10 genes to choose. For the second gene, the number of genes to choose is 9. The information needed for the order of expression is: