math help

What is 9/10 + 7/9?

What is 9/10 + 7/9?

Here's how to add

9
10
+
7
9

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 9 by 9, and get 81, then we multiply 10 by 9 and get 90.

9/10 times 9

Now for the second term. You multiply 7 by 10, and get 70, then multiply 10 by 9 and get 90.

7/9 times 10

We now have a new problem, that looks like this:

81
90
+
70
90

Step 2

Since our denominators match, we can add the numerators.

81 + 70 = 151

Answer:

151
90

Step 3

Now, do we need to simplify this fraction?

First, we attempt to divide it by 2...

No good. So next you try the next prime number, which is 3...

No good. So next you try the next prime number, which is 5...

No good. So next you try the next prime number, which is 7...

No good. So next you try the next prime number, which is 11...

No good. So next you try the next prime number, which is 13...

No good. So next you try the next prime number, which is 17...

No good. So next you try the next prime number, which is 19...

No good. So next you try the next prime number, which is 23...

No good. So next you try the next prime number, which is 29...

No good. So next you try the next prime number, which is 31...

No good. So next you try the next prime number, which is 37...

No good. So next you try the next prime number, which is 41...

No good. So next you try the next prime number, which is 43...

No good. So next you try the next prime number, which is 47...

No good. So next you try the next prime number, which is 53...

No good. So next you try the next prime number, which is 59...

No good. So next you try the next prime number, which is 61...

No good. So next you try the next prime number, which is 67...

No good. So next you try the next prime number, which is 71...

No good. So next you try the next prime number, which is 73...

No good. So next you try the next prime number, which is 79...

No good. So next you try the next prime number, which is 83...

No good. So next you try the next prime number, which is 89...

No good. So next you try the next prime number, which is 97...

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

And we're done! Here's the final answer to 9/10 + 7/9

9
10
+
7
9
=
151
90
© 2014 Randy Tayler