In this manuscript, motivated by the fact that the division 1/3 = 0,33......is not exact, while for example one can divide a cake into three exact pieces. We describe a logical procedure to divide r into m exact parts. We also show the corresponding exact formIn this manuscript, motivated by the fact that the division 1/3 = 0,33......is not exact, while for example one can divide a cake into three exact pieces. We describe a logical procedure to divide r into m exact parts. We also show the corresponding exact formula.[+][-]