math help

What is 7/10 + 8/9?

What is 7/10 + 8/9?

This is how to add

7
10
+
8
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 7 by 9, and get 63, then we multiply 10 by 9 and get 90.

7/10 times 9

Do the same for the second term. We multiply 8 by 10, and get 80, then multiply 10 by 9 and get 90.

8/9 times 10

The problem now has new fractions to add:

63
90
+
80
90

Step 2

Since our denominators match, we can add the numerators.

63 + 80 = 143

This yields the answer

143
90

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...

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...

Nope. Try the next prime number, 73...

Nope. Try the next prime number, 79...

Nope. Try the next prime number, 83...

Nope. Try the next prime number, 89...

Nope. Try the next prime number, 97...

No good. 97 is larger than 90. So we're done reducing.

Congratulations! Here's your final answer to 7/10 + 8/9

7
10
+
8
9
=
143
90
© 2014 Randy Tayler