math help

What is 4/40 + 2/12?

What is 4/40 + 2/12?

This is how you add

4
40
+
2
12

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 4 by 12, and get 48, then we multiply 40 by 12 and get 480.

4/40 times 12

Do the same for the second term. We multiply 2 by 40, and get 80, then multiply 40 by 12 and get 480.

2/12 times 40

The problem now has new fractions to add:

48
480
+
80
480

Step 2

Since our denominators match, we can add the numerators.

48 + 80 = 128

This yields the answer

128
480

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:

128
480
÷ 2 =
64
240

Now, try the same number again.

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

64
240
÷ 2 =
32
120

Now, try the same number again.

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

32
120
÷ 2 =
16
60

Now, try the same number again.

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

16
60
÷ 2 =
8
30

Now, try the same number again.

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

8
30
÷ 2 =
4
15

Now, try the same number again.

Nope. Try the next prime number, 3...

Nope. Try the next prime number, 5...

No good. 5 is larger than 4. So we're done reducing.

Congratulations! Here's your final answer to 4/40 + 2/12

4
40
+
2
12
=
4
15
© 2014 Randy Tayler