How many moles are there in a certain mass of a substance?

Number of moles of substance in a certain mass of a substance may be obtained as follows. Let,

Mass of the substance = Wg

Molar mass of the substance = Mg/mol

Then,

No. of moles of the substances= ^Wg / _Mg/mol =^W / _M mol

Or the No. of moles of a substance= ^{Mass of the substances in grams} / _{Molar mass of the substance in grams person mole}