Why is the logarithm of LG's 0.00001 equal to - 5?

Why is the logarithm of LG's 0.00001 equal to - 5?

lg0.00001=lg(1/10000)=lg(10e-5)
Where LG is based on ten, according to the relevant formula of logarithm
Easy to get what you want
1/10000=(1/10)5=((10)e-1)5