Division with Fractions 1 and 3/4 divided by 1/2

This is an example from Liping Ma's book:

Using Decimals
How much is 1.75 divided by .5?
1.75/.5 = 3.5


Using Fractions
1 and 3/4 divided by 1/2
1 and 3/4 = 7/4
7/4 divided by 1/2
How many half cups are in 7/4 cups?
1 half cup = 1/2
2 half cups = 2/2 = 1
3 half cups = 3/2
4 half cups = 4/2 = 2 -- this is too much

7/4 divided by 1/2
multiply 7/4 by the reciprocal of 1/2
7/4 x 2/1 = 14/4 = 7/2 = 3 and 1/2

Division with Fractions is "a topic at the summit of arithmetic". In the introduction, she asks a division with fractions question: 13/4 divided by 1/2 and offers three additional problem-solving methodologies (besides Keep, Change, Flip) -- Dividing Using Decimals, Applying the Distributive Law and You Don't Have to Multiply.

Invert and multiply...which one????

Oh, just flip it upside down and then multiply (“invert and multiply”).
But they are not sure which one to flip!!

Students learn this in late elementary, but when asked “Why?”,
they will say “Oh, it’s the rule”.

An example such as “How much is 12 divided by ½?” can illustrate the concept and learners can follow this example rather than a rule!!

How many half dollars are in $12?
How many half inches in 1 foot?

12 x 2/1 = 24!! ;)