Fraction of an acre

Question

Mr. Chagall's garden covers 2/5 of an acre of land. He divides the land into 4 equal sections. What fraction of an acre is each section of the garden?

Answer 1

Hi Princess-- think of it this way:

 

Can we turn 2/5 into something that's more easily divisible by 10?

 

What if we turned 2/5 into some number of 10ths? In order to get 10ths in the denominator, we need to multiply the 5 that's there TIMES 2.

 

Which means we also have to multiply the numerator (top number) TIMES 2. ("Whatever you do to the bottom, you do to the top.")

 

So 2/5 can be called 4/10 instead.

 

Now, if he's got 4/10 of an acre, and he's going to divide it into 4 equal sections, each section will end up being...

 

1/10 of an acre.

 

The OTHER way you can do it goes like this:

 

When you have to divide a fraction by "something," you can use the "keep-change-flip" trick:

 

Keep the first number as-is; change the division sign to multiplication; and flip the number to its reciprocal.

 

(if that second number is a whole number, its reciprocal is 1/the number, "one over the number, so for example the reciprocal of 4 is 1/4.  If the second number is already a fraction, just flip it over, so for example 2/3 would flip to 3/2.)

 

SOO... you can change the equation to 2/5 x 1/4, and multiply straight across to get 2/20, which simplifies to the same 1/10 we got before.

 

So remember "keep-change-flip," but also remember to look at the numbers and see if there is an equivalent fraction you can use to make the equation more manageable, as we did in the first example.

 

Hope this helps!

 

Matt in New York