math help

What is 72/63 + 9/10?

What is 72/63 + 9/10?

Here's how to add

72
63
+
9
10

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 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 9 by 63, and get 567, then multiply 63 by 10 and get 630.

9/10 times 63

The problem now has new fractions to add:

720
630
+
567
630

Step 2

Since our denominators match, we can add the numerators.

720 + 567 = 1287

This yields the answer

1287
630

Step 3

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

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:

1287
630
÷ 3 =
429
210

Now, try the same number again.

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

429
210
÷ 3 =
143
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 + 9/10

72
63
+
9
10
=
143
70
© 2014 Randy Tayler