Try this from Wikipedia:
To calculate the property tax, the authority will multiply the assessed value of the property by the mill rate and then divide by 1,000.
First, get your HPR Tax rate at http://troymi.gov/Taxes/. Just type in your address and all your tax info pops up.
Mine is 109,890. (That means Oakland County believes my property is worth about double, or $218,000.)
I multiply it by 0.9885 (Proposal 1's millage amount) and get 108,626.
I divide it by 1,000 and I get $108.62 per year, or $9.05 a month to keep the library open.
Seems like a no-brainer to me.