math help

What is 87/100 - 1/4?

What is 87/100 - 1/4?

Here's how to subtract 1/4 from 87/100:

87
100
1
4

Step 1

We can't subtract two fractions with different denominators. So you need to get a common denominator. To do this, you'll multiply the denominators times each other... but the numerators have to change, too. They get multiplied by the other term's denominator.

So we multiply 87 by 4, and get 348.

Then we multiply 1 by 100, and get 100.

Next we give both terms new denominators -- 100 × 4 = 400.

So now our fractions look like this:

348
400
100
400

Step 2

Since our denominators match, we can subtract the numerators.

348 − 100 = 248

So the answer is:

248
400

Step 3

Last of all, we need to simplify the fraction, if possible. Can it be reduced to a simpler fraction?

To find out, we try dividing it by 2...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

248
400
÷ 2 =
124
200

Let's try dividing by 2 again...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

124
200
÷ 2 =
62
100

Let's try dividing by 2 again...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

62
100
÷ 2 =
31
50

Let's try dividing by 2 again...

Nope! So now we try the next greatest prime number, 3...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

Nope! So now we try the next greatest prime number, 29...

Nope! So now we try the next greatest prime number, 31...

Nope! So now we try the next greatest prime number, 37...

No good. 37 is larger than 31. So we're done reducing.

There you have it! The final answer is:
87
100
1
4
=
31
50