What did Avagandro do to help figure the mole?

How did Avagandro help figure out the mole and how do scientists use it today?!What did Avagandro do to help figure the mole?
Scientists use it today to calculate the amount of a substance, number of particles, that they have. The molecular mass of something times the number of moles of the substance equals the mass in grams of the substance. For example 1 mol of H2O equals 18g, and equals 6.02810^23 particles of water.What did Avagandro do to help figure the mole?
Avogrado did not develop the number directly, but it was named after him to honor his work. There are actually numerous methods for calculating this number even though the exact number is still out of reach, just like pi. Scientists use this number for many applications such as chemical concentrations. Refer to the listed source to find the latest number, methods and uses.
He came up with the number of particles in a mole of a substance i.e. 6X10^23. It's called Avogadro's number and it's used all the time today as the definition of a mole and to calculate the number of particles in a certain amount of a substance.