Exodus 30:13

30:13 Everyone who crosses over to those who are numbered is to pay this: a half shekel according to the shekel of the sanctuary (a shekel weighs twenty gerahs). The half shekel is to be an offering to the Lord.

Leviticus 27:25

27:25 Every conversion value must be calculated by the standard of the sanctuary shekel; twenty gerahs to the shekel.

Numbers 3:47

3:47 collect five shekels for each one individually; you are to collect this amount in the currency of the sanctuary shekel (this shekel is twenty gerahs).