math help

What is 21/33 + 4/8?

What is 21/33 + 4/8?

This is how we add

21
33
+
4
8

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 21 by 8, and get 168, then we multiply 33 by 8 and get 264.

21/33 times 8

Do the same for the second term. We multiply 4 by 33, and get 132, then multiply 33 by 8 and get 264.

4/8 times 33

The problem now has new fractions to add:

168
264
+
132
264

Step 2

Since our denominators match, we can add the numerators.

168 + 132 = 300

This yields the answer

300
264

Step 3

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

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:

300
264
÷ 2 =
150
132

Let's try dividing by that again...

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

150
132
÷ 2 =
75
66

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:

75
66
÷ 3 =
25
22

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...

No good. 23 is larger than 22. So we're done reducing.

There you have it! Here's the final answer to 21/33 + 4/8

21
33
+
4
8
=
25
22
© 2014 Randy Tayler