math help

What is 3/18 + 6/7?

What is 3/18 + 6/7?

This is how to add

3
18
+
6
7

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 3 by 7, and get 21, then we multiply 18 by 7 and get 126.

3/18 times 7

Do the same for the second term. We multiply 6 by 18, and get 108, then multiply 18 by 7 and get 126.

6/7 times 18

The problem now has new fractions to add:

21
126
+
108
126

Step 2

Since our denominators match, we can add the numerators.

21 + 108 = 129

This yields the answer

129
126

Step 3

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

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

Nope. Try the next prime number, 3...

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

129
126
÷ 3 =
43
42

Now, try the same number again.

Nope. Try the next prime number, 5...

Nope. Try the next prime number, 7...

Nope. Try the next prime number, 11...

Nope. Try the next prime number, 13...

Nope. Try the next prime number, 17...

Nope. Try the next prime number, 19...

Nope. Try the next prime number, 23...

Nope. Try the next prime number, 29...

Nope. Try the next prime number, 31...

Nope. Try the next prime number, 37...

Nope. Try the next prime number, 41...

Nope. Try the next prime number, 43...

No good. 43 is larger than 42. So we're done reducing.

Congratulations! Here's your final answer to 3/18 + 6/7

3
18
+
6
7
=
43
42
© 2014 Randy Tayler