math help

What is 4/40 + 1/7?

What is 4/40 + 1/7?

This is how we add

4
40
+
1
7

Step 1

We can't add two fractions with different denominators (the bottom number). So you need to get a common denominator - both bottom numbers need to match. To do this, you'll multiply the denominators times each other... but the numerators have to change, too. They get multiplied by the other term's denominator.

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

4/40 times 7

Do the same for the second term. We multiply 1 by 40, and get 40, then multiply 40 by 7 and get 280.

1/7 times 40

So now our fractions look like this:

28
280
+
40
280

Step 2

Since our denominators match, we can add the numerators.

28 + 40 = 68

Now we have an answer.

68
280

Step 3

Last of all, we need to simplify the fraction, if possible. Can it be reduced to a simpler fraction?

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:

68
280
÷ 2 =
34
140

Now, try the same number again.

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

34
140
÷ 2 =
17
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...

No good. 19 is larger than 17. So we're done reducing.

Congratulations! Here's your final answer to 4/40 + 1/7

4
40
+
1
7
=
17
70
© 2014 Randy Tayler