math help

What is 21/33 + 3/9?

What is 21/33 + 3/9?

This is how we add

21
33
+
3
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 21 by 9, and get 189, then we multiply 33 by 9 and get 297.

21/33 times 9

Do the same for the second term. We multiply 3 by 33, and get 99, then multiply 33 by 9 and get 297.

3/9 times 33

The problem now has new fractions to add:

189
297
+
99
297

Step 2

Since our denominators match, we can add the numerators.

189 + 99 = 288

This yields the answer

288
297

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:

288
297
÷ 3 =
96
99

Let's try dividing by that again...

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

96
99
÷ 3 =
32
33

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 32. So we're done reducing.

There you have it! Here's the final answer to 21/33 + 3/9

21
33
+
3
9
=
32
33
© 2014 Randy Tayler