math help

What is 72/63 + 3/10?

What is 72/63 + 3/10?

Let's add

72
63
+
3
10

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 72 by 10, and get 720, then we multiply 63 by 10 and get 630.

72/63 times 10

Do the same for the second term. We multiply 3 by 63, and get 189, then multiply 63 by 10 and get 630.

3/10 times 63

So now our fractions look like this:

720
630
+
189
630

Step 2

Since our denominators match, we can add the numerators.

720 + 189 = 909

Now we have an answer.

909
630

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. Try the next prime number, 3...

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

909
630
÷ 3 =
303
210

Now, try the same number again.

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

303
210
÷ 3 =
101
70

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...

Nope. Try the next prime number, 59...

Nope. Try the next prime number, 61...

Nope. Try the next prime number, 67...

Nope. Try the next prime number, 71...

No good. 71 is larger than 70. So we're done reducing.

Congratulations! Here's your final answer to 72/63 + 3/10

72
63
+
3
10
=
101
70
© 2014 Randy Tayler