Posted by Rosedala on .
Whichh is cheaper of the 2 following boxes?:
One liter (1000 ml) per bottle, 12 in a box: $60 per box
OR:
Three quarter (750 ml) liter per bottle, 12 in a box: $40 per box
thank you so very much!

Arithmetic 
Ms. Sue,
1,000 ml * 12 = ?
Divide 60 by the above number to get the cost per ml.
750 ml * 12 = ?
Divide 40 by the above number to get the cost per ml. 
Arithmetic 
Rosedala,
I'm sorry Ms. Sue, but I'm an arithmeticchallenged adult and my face is quite red:
I divided 60 by 1000 and got 0.06
Did the same with 40 and got 0.0533
How do I know which is cheaper since the 2nd one has less content (only 3/4 of liter as opposed to one full liter?
Please forgive my taking your time again, and thanks so very much! :o) 
Arithmetic 
Ms. Sue,
1000 * 12 is not 1000
1000 * 12 = 12,000
60/12,000 = $0.005 per ml.
The way to compare these is to find the cost per ml.
What is the cost per ml for the other box? 
Arithmetic 
Rosedala,
Thank Ms. Sue!
I multiplied 750 x 12 = 9000
I divided 9000 by 12 = 0.00666
So...the smaller bottles are then more expensive despite the fact that the price tag is lower.
Thanks again a lot! :) 
Arithmetic 
Ms. Sue,
Why did you divide 9,000 by 12?
You need to divide 9,000 ml by the total cost. 
Arithmetic 
Rosedala,
Oh I'm sorry (I'll never get this into my cerebrum!)...
The lower price tag is indeed cheaper. This time I got 0.00444. This makes it one tenth of a cent cheaper?
I'll write this little formula for my future purchases. Thank you so much! 
Arithmetic 
Rachael,
1 litre per bottle