math help

What is 78/10 + 1/9?

What is 78/10 + 1/9?

Here's how to add

78
10
+
1
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 78 by 9, and get 702, then we multiply 10 by 9 and get 90.

78/10 times 9

Do the same for the second term. We multiply 1 by 10, and get 10, then multiply 10 by 9 and get 90.

1/9 times 10

The problem now has new fractions to add:

702
90
+
10
90

Step 2

Since our denominators match, we can add the numerators.

702 + 10 = 712

This yields the answer

712
90

Step 3

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

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:

712
90
÷ 2 =
356
45

So far so good... let's try to divide by that number again.

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. 47 is larger than 45. So we're done reducing.

And we're done! Here's the final answer to 78/10 + 1/9

78
10
+
1
9
=
356
45
© 2014 Randy Tayler