math help

What is 1/15 + 11/12?

What is 1/15 + 11/12?

Here's how we add

1
15
+
11
12

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 1 by 12, and get 12, then we multiply 15 by 12 and get 180.

1/15 times 12

Now for the second term. You multiply 11 by 15, and get 165, then multiply 15 by 12 and get 180.

11/12 times 15

We now have a new problem, that looks like this:

12
180
+
165
180

Step 2

Since our denominators match, we can add the numerators.

12 + 165 = 177

That gives us the sum, which is

177
180

Step 3

Now, do we need to simplify this fraction?

First, we attempt to divide it by 2...

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:

177
180
÷ 3 =
59
60

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...

Nope! So now we try the next greatest prime number, 41...

Nope! So now we try the next greatest prime number, 43...

Nope! So now we try the next greatest prime number, 47...

Nope! So now we try the next greatest prime number, 53...

Nope! So now we try the next greatest prime number, 59...

Nope! So now we try the next greatest prime number, 61...

No good. 61 is larger than 59. So we're done reducing.

There you have it! Here's the final answer to 1/15 + 11/12

1
15
+
11
12
=
59
60
© 2014 Randy Tayler

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