# Arithmetic

posted by 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 - ,

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 - ,

I'm sorry Ms. Sue, but I'm an arithmetic-challenged 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 - ,

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 - ,

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 - ,

Why did you divide 9,000 by 12?

You need to divide 9,000 ml by the total cost.

• Arithmetic - ,

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 - ,

1 litre per bottle