math help

What is 87/100 + 9/12?

What is 87/100 + 9/12?

Here's how you add

87
100
 +
9
12

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 87 by 12, and get 1044, then we multiply 100 by 12 and get 1200.

87/100 times 12

Do the same for the second term. We multiply 9 by 100, and get 900, then multiply 100 by 12 and get 1200.

9/12 times 100

So now our fractions look like this:

1044
1200
 +
900
1200

Step 2

Since our denominators match, we can add the numerators.

1044 + 900 = 1944

So the answer is:

1944
1200

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...

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

1944
1200
 ÷ 2 =
972
600

Now, try the same number again.

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

972
600
 ÷ 2 =
486
300

Now, try the same number again.

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

486
300
 ÷ 2 =
243
150

Now, try the same number again.

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

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

243
150
 ÷ 3 =
81
50

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...

Nope. Try the next prime number, 47...

Nope. Try the next prime number, 53...

No good. 53 is larger than 50. So we're done reducing.

Congratulations! Here's your final answer to 87/100 + 9/12

87
100
 +
9
12
 =
81
50
© 2014 Randy Tayler

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