math help

What is 31/12 + 2/9?

What is 31/12 + 2/9?

Here's how you add

31
12
+
2
9

Step 1

Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator.

Now you multiply 31 by 9, and get 279, then we multiply 12 by 9 and get 108.

31/12 times 9

Do the same for the second term. We multiply 2 by 12, and get 24, then multiply 12 by 9 and get 108.

2/9 times 12

The problem now has new fractions to add:

279
108
+
24
108

Step 2

Since our denominators match, we can add the numerators.

279 + 24 = 303

The sum we get is

303
108

Step 3

The last step is to reduce the fraction if we can.

To find out, we try dividing 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:

303
108
÷ 3 =
101
36

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 36. So we're done reducing.

There you have it! Here's the final answer to 31/12 + 2/9

31
12
+
2
9
=
101
36
© 2014 Randy Tayler