math help

What is 21/33 + 1/5?

What is 21/33 + 1/5?

Here's how we add

21
33
+
1
5

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 21 by 5, and get 105, then we multiply 33 by 5 and get 165.

21/33 times 5

Do the same for the second term. We multiply 1 by 33, and get 33, then multiply 33 by 5 and get 165.

1/5 times 33

So now our fractions look like this:

105
165
+
33
165

Step 2

Since our denominators match, we can add the numerators.

105 + 33 = 138

Now we have an answer.

138
165

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...

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:

138
165
÷ 3 =
46
55

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...

No good. 47 is larger than 46. So we're done reducing.

There you have it! Here's the final answer to 21/33 + 1/5

21
33
+
1
5
=
46
55
© 2014 Randy Tayler