Heres One for the Math People

Sounds relatively simple.
He drinks 15 oz of breastmilk per day. You replace (pump?) 12 oz. per day. Net loss of 3 oz per day.
15-12= 3 oz per day
So, if you have 19 jars of 16 oz each, using it at the rate of 3 oz. per day, then you would have 5 1/3 days per jar. Which, multiplied times 19 jars is about 101 days. (101 1/3 days actually).

Anybody else want to confirm ?

For Riley: Well, I didn't round anything, and that has a cumulative effect on the numbers. Because as you added another layer of days for each, you run out of days to add to sooner, because of the rounding. Additionally, you neglected to account for the difference in what was consumed (15 oz) vs the bottle size (16 oz). So one bottle does not equal one day. Technically.
In reality, it is probably somewhere in between our answers, b/c the numbers I used do not account for variations in consumption or production that are likely but unpredictable. :))

19 jars * 16 oz = 304 oz.
x = # of days left

304 - (15-12)x = 304 - 3x

after x number of days, there will be 0 oz bm left, so 304-3x=0; add 3x to both sides, giving 304 = 3x; divide by 3, getting the 101.33.

I would have just said Bridgett & Victoria were right, but Riley asked a why. :)

Riley, I didn't check it, but my guess would be that without rounding, you would have come up to the 101 as well. Once you start dropping decimals, you get roundoff error.

Yep, according to my calculations, and assuming that the child eats the same amount and mom is able to replace the same amount over time, Victoria is correct, 101.33 days.

Hubby is a math whiz and he double-checked my work :)

Oh my gosh, this makes me head spin. So not a math person.

I bet there's a faster way/formula to do this, but here's my breakdown (wonder if it will be the same as other peoples'?)

Whenever I have to round (half days, I'm going to round down). I'm also just using 1 jar for day, since you're only an ounce off, and anything you don't use you lose. AKA 16oz per day, not 15.

19 days you have

12*19= 228 / 16 (your jar size) = 14 more days +
12*14 / 16 = 10
12*10/16= 7
12*7/16= 5
12*5/16= 3
12*3/16=2
12*2/16=1

19+14+10+7+5+3+2+1 = 61

BASICALLY = 61 days BUT subtract 1/3 to plan for growth spurts, spills, etc.

Count on 40 more days, but you may have as much as 2 more months as long as intake doesn't go up, production goes down, and you don't spill!
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<Grin> Alright! If I'm wrong... why?

At the end of 19 days, there will be 14 new jars from the 12oz per day.
At the end of 14 days, there will be 10 new jars.

No?