Conversions and Significant Digits

Today in class we learned about conversions and Significant digits.

Conversions are when you take something like ounces and convert it to tons. When you convert, it is usually to make things easier to count with, or to make things in larger scales to count with. When you go to the store, you obviously want to get something measured in ounces rather than tons. 
When we did the conversions we started with a chart
Convert 2.500 kilograms into milligrams
You start with 2.500 Kilograms
You know that 1 kilogram= 1000grams
You also know that 1 Gram= 1000 milligrams
so you multiply across and get 25,000,000 milligrams

When you are at home, using things like ounces, and cups are a lot easier.  When you have a conversion chart like this, it is also easy to convert to things without having to do that. Knowing how to do it is also very important in case you do not have a chart like this.

Significant digits are also very useful in every day math.  Significant numbers is pretty much a large word for rounding.  When you have a number that has a decimal you can round it to the amount of significant numbers that it has;however, you do not round when you have things like 2 arms and 2 legs, you do not have 2.1 arms, or 1.8 legs.  You use the term only in digits that you are using in math terms.

When you are looking at a decimal like 0.8904 you start at the first non-zero number on the left. 

So that decimal would have 4 significant digits.

A decimal like .00245 would only have 3 because you start counting after the two zeros. 

Here is a good conversion website to use if you are having trouble with conversion.