math help

What is 20/64 + 3/9?

What is 20/64 + 3/9?

Here's how you add

20
64
+
3
9

Step 1

We can't add two fractions with different denominators (the bottom number). So you need to get a common denominator - both bottom numbers need to match. 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 20 by 9, and get 180, then we multiply 64 by 9 and get 576.

20/64 times 9

Do the same for the second term. We multiply 3 by 64, and get 192, then multiply 64 by 9 and get 576.

3/9 times 64

So now our fractions look like this:

180
576
+
192
576

Step 2

Since our denominators match, we can add the numerators.

180 + 192 = 372

So the answer is:

372
576

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:

372
576
÷ 2 =
186
288

Let's try dividing by that again...

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

186
288
÷ 2 =
93
144

Let's try dividing by that again...

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

Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:

93
144
÷ 3 =
31
48

Let's try dividing by that again...

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! Here's the final answer to 20/64 + 3/9

20
64
+
3
9
=
31
48
© 2014 Randy Tayler