math help

What is 4/40 + 4/7?

What is 4/40 + 4/7?

This is how to add

4
40
+
4
7

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 4 by 7, and get 28, then we multiply 40 by 7 and get 280.

4/40 times 7

Now for the second term. You multiply 4 by 40, and get 160, then multiply 40 by 7 and get 280.

4/7 times 40

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

28
280
+
160
280

Step 2

Since our denominators match, we can add the numerators.

28 + 160 = 188

That gives us the sum, which is

188
280

Step 3

Now, do we need to simplify this fraction?

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

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

188
280
÷ 2 =
94
140

Now, try the same number again.

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

94
140
÷ 2 =
47
70

Now, try the same number again.

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...

No good. 53 is larger than 47. So we're done reducing.

Congratulations! Here's your final answer to 4/40 + 4/7

4
40
+
4
7
=
47
70
© 2014 Randy Tayler