## Chem – Multiplication and Division Together

How do you do Multiplication and Division on a calculator?

The way that division problems can be written like fractions is usually the most useful in science. It is the most common way written and the easiest to think about when you have to do any rearrangements of equations. In future chapters, we will also try working with multiplication and division simultaneously, and we have to know how to deal with that.

Examples: Solve the combined multiplication and division problems. I demonstrate how these examples are put into your calculator with these two different links. VIDEO Multiplication and division examples with a regular calculator. VIDEO Multiplication and division with a graphing calculator.

 50 / ((2)(5)) = 5 (6*10) / (2 *4(5)) = 1.5 (15 * 2) / 3 = 10

Another way to represent multiplication and division problems is to weave them together into what teachers will call “train tracks” or multiplying by ratios. Due to restrictions on how I am able to write math examples out on a word processor, I will explain my example after I write it.

Examples: Solve the combined multiplication and division problems. They are demonstrated by the links in the examples above.

 10 15 5 = 12.5 30 2

The above means: (10 * 15 * 5) / (30 * 2) = 12.5

 20 1 8 = 8 4 2.5 2

The above means: (20 * 1 * 8 ) / (4 * 2.5 * 2) = 8

PRACTICE PROBLEMS: Solve the following problems.

 8 6 10 2 4 3

The above = 20

 3.8 2.1 7.6 2.5 9.6 1.1

The above = 2.30

 12 82 36 70 2 54

The above = 4.69

 5.6 3.1 2.3 1.8 10.4 9.2

The above = 0.23  