The deficient numbers were introduced by Nicomachus in the *Arithmetic Introductory*.

They are those whose sum of their own dividers is less than this number. For example, **14** is a poor number because:

14 > 1+2+7=10

The deficient numbers were introduced by Nicomachus in the *Arithmetic Introductory*.

They are those whose sum of their own dividers is less than this number. For example, **14** is a poor number because:

14 > 1+2+7=10