The time it takes a black hole to evaporate is proportional to the cube of its mass. If you graph mass-cubed versus time, it decreases linearly at about 100 mil

The time it takes a black hole to evaporate is proportional to the cube of its mass. If you graph mass-cubed versus time, it decreases linearly at about 100 million cubic tonnes per second. The actual mass decreases at a rate that's inversely proportional to the square of the mass.