### Skills Assignment 4: Reciprocal

Tuesday, May 5, 2009
Today, we were assigned yet another blog post. We have to define the word reciprocal, explain how it's used in math, use reciprocal in 2 questions (3/4 divided by 2/5 and 2/5 divided by 3/4) and guess if it's either more than or less than one.

Definition:
In mathematics, the reciprocal can be referred to multiplicative inverse. When 1 is divided by x, multiplied by x, it will give the product of 1.

In general, the fraction's reciprocal is attained by alternating the numerator and the denominator.

How is it used in math?
Using reciprocal is easier and quicker than dividing the fraction.  It's used when you are doing ratio tables. We use the denominator to multiply the fraction, then divide it by the numerator to make a whole number.

Guesstimate:
3/4  / 2/5. I think it's more than 1.
2/5 / 3/4. I think it's more than 1.

Examples:
3/4 divided by 2/5.
As you can see, we used reciprocal to get a whole number; we used the denominator (5) to multiply the fraction, then divided it by the numerator (2). What you do on one side of the ratio table, you have to do the same thing to the other. But, we weren't able to divide so we had to figure out how many times does 4 goes into 15. Then you'll have your answer.

Again, we did the same thing as the first question.