math help

What is 21/63 + 1/10?

What is 21/63 + 1/10?

Here's how we add

21
63
+
1
10

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 21 by 10, and get 210, then we multiply 63 by 10 and get 630.

21/63 times 10

Now for the second term. You multiply 1 by 63, and get 63, then multiply 63 by 10 and get 630.

1/10 times 63

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

210
630
+
63
630

Step 2

Since our denominators match, we can add the numerators.

210 + 63 = 273

That gives us the sum, which is

273
630

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...

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

273
630
÷ 3 =
91
210

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 5...

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

Are both the numerator and the denominator evenly divisible by 7? Yes! So we reduce it:

91
210
÷ 7 =
13
30

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 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. 17 is larger than 13. So we're done reducing.

And we're done! Here's the final answer to 21/63 + 1/10

21
63
+
1
10
=
13
30
© 2014 Randy Tayler