Ezekiel 45:12, in discussing just weights and measures, says:
וְהַשֶּׁקֶל, עֶשְׂרִים גֵּרָה; עֶשְׂרִים שְׁקָלִים חֲמִשָּׁה וְעֶשְׂרִים שְׁקָלִים, עֲשָׂרָה וַחֲמִשָּׁה שֶׁקֶל--הַמָּנֶה, יִהְיֶה לָכֶם.
And the shekel shall be twenty gerahs; twenty shekels, five and twenty shekels, ten, and five shekels, shall be your maneh.
That seems like a pretty roundabout way of saying sixty shekels. Why is it expressed this way? Is there symbolism in the numbers chosen? Were, 20, 25, etc shekels common units of value already in use?
(Somebody asked this question over on Biblical Hermeneutics but as of this writing it has not received a credible answer, so I thought I'd ask here.)