Why does Ezekiel describe the maneh as 20 + 25 + 10 + 5 shekels instead of just saying 60?

Question

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.)

Answer 1

Rashi to that verse, and Tosafos in Bechoros 5a (s.v. Esrim), ask this question. They answer (based on the Targum of the verse) that there were actually separate measuring utensils that had to be made in the listed denominations. See there for the detailed explanation of what each one was used for.

Update: Here is how it is presented by D.A.F. Resources:

TOSFOS (DH Esrim) explains that these three parts represent the actual measuring units used in the Beis ha'Mikdash. "Twenty Shekels" was used as a measure for a third of a Maneh of Kodesh. "Twenty-five Shekels" was used to measure one plain (non-Kodesh) Maneh. "Fifteen Shekels" measured one quarter of a Maneh of Kodesh.

Answer 2

• :/.גמרא בבא בתרא צ

  אמר שמואל: אין מוסיפין על המדות יותר משתות, ולא על המטבע יתר משתות והמשתכר אל ישתכר יותר משתותאמר... אמר רב חסדא, שמואל קרא אשכח ודרש: +יחזקאל מ"ה+ והשקל עשרים גרה עשרים שקלים חמשה ועשרים שקלים עשרה וחמשה שקל המנה יהיה לכם,מנה - מאתן וארבעין הוו! אלא שמע מינה תלת, ש"מ: מנה של קדש כפול היה, ושמע מינה: מוסיפין על המדות ואין מוסיפין יותר משתות, ושמע מינה: שתותא מלבר

• it would apear that the reason it is written as such is to show the three things mentioned in the גמרא: the מנה of the בית המיקדש was double the usual amount, you can revalue money, but not more than a sixth, and that sixth is "from the outside", i.e. it is actually a fifth but when you add all the parts together it is 6/5.

• רשב''ם שם ד''ה– עשרים שקלים חמשה ועשרים שקלים עשרה וחמשה שקל - שלש חשבונות הללו ביחד המנה יהיה לכם ויש לומר דיש מקומות שהמנה חמשה עשר סלעים ויש עשרים סלעים ויש חמשה ועשרים לכך נאמר שלשת המנים הללו המנה של קודש יהיה לכם

• translation: ... One may say that there are places that the mana is 15 sheqalim and another (place) that it is 20 sheqalim and another that it is 25 sheqalim, therefore it (the pasuk) says these three types of mana