In Hour 2, "Using the Script Editing Window," and Hour 3, "Learning to Program," you learned how variables can hold numbers. They can hold integers, such as 7, and floating point numbers , such as 1.3574. #### Basic Operators You also learned about basic numerical operators. Let's review them. The ` + ` and ` - ` symbols allow you to add and subtract numbers. The ` * ` symbol is for multiplication. The ` / ` symbol is for division. You can also use ` += ` , ` -= ` , ` *= ` , and ` /= ` to simplify your code. For instance, the following two lines perform the same operation. In both cases, 7 is added to "a": a = a + 7; a += 7; #### Comparison Operators You can compare two numbers with the ` == ` symbol to see whether they are equal. You can also use the ` < ` or ` > ` symbols as less than or greater than. The ` <= ` and ` >= ` symbols are for less than or equal to and greater than or equal to. In ActionScript, you can freely compare integers and floating point numbers. For instance, a variable containing 7.2 would be greater than a variable containing 7. #### ` Math.abs ` The ` Math ` object is a collection of functions that work with numbers. For instance, the ` Math.abs ` function returns the absolute value of a number. This is simply the number without the positive or negative sign. So -7 returns 7, and 7 returns 7. Here is an example: trace(Math.abs(-7)); #### ` Math.round ` If you are using floating point numbers, but want to display them to the user , you may decide to display them as integers instead of with the part of the number after the decimal point. The most straightforward function for this is ` Math.round ` , which rounds a floating number up or down to the nearest integer. So 7.2 becomes 7, and 7.8 becomes 8. trace(Math.round(7.2)); trace(Math.round(7.8)); #### ` Math.ceil ` , ` Math.floor ` Two other functions that convert floating point numbers to integers are ` Math.ceil ` and ` Math.floor ` . The first rounds a number up to the nearest integer, and the second rounds a number down. So the result of both these examples is 7: trace(Math.ceil(6.1)); trace(Math.floor(7.9)); #### ` Math.min ` , ` Math.max ` You can compare two numbers and get the smallest or largest of the two using ` Math.min ` and ` Math.max ` . For instance, if "a" is 5, and "b" is 4, ` Math.min(a,b) ` returns 4, and ` Math.max(a,b) ` returns 5. #### ` Math.pow ` If you ever need to raise a number by a power, you can do so with the ` Math.pow ` function. The first parameter is the number, and the second is the power. So to get 4 to the third power, you can do this: trace(Math.pow(4,3)); #### ` Math.sqrt ` You can also use numbers less than 1 as the power in ` Math.pow ` . This means that you can use ` Math.pow(x,.5) ` to get the square root of x. Or, you could use the shortcut function ` Math.sqrt ` . trace(Math.sqrt(4)); |