'Twenty' in the Bible

Your valuation shall be of a male from twenty years old even to sixty years old, even your valuation shall be fifty shekels of silver, after the shekel of the sanctuary.

If the person is from five years old even to twenty years old, then your valuation shall be for a male twenty shekels, and for a female ten shekels.

All your valuations shall be according to the shekel of the sanctuary: twenty gerahs to the shekel.