The Minoans' vigesimal numbering system was based on 20.

a. True

b. False

It is true that the Minoans' vigesimal numbering system was based on 20. Just like our decimal numeral system is based on 10 (we have single digit numbers 1-9, and then double digits), vigesimal system has 20 of such digits, ranging from 1 to 9, and then continuing from A to K to denote other numbers, until our number 20.