1. CHAPTER FOUR VARIABLES AND CONSTANTS
COMPUTER MATHEMATICS
CHAPTER FOUR
VARIABLES AND CONSTANTS

2. USING VARIABLES Variable – memory location that stores a value
Variables must be declared with a DIM statement
DIM – includes identifier and data type
Identifier – name of variables; how it is referred to within the program
Data Type – kind of value to store

3. USING VARIABLES Example: DIM dblRadius As Double
dblRadius – variable or identifier; begins with dbl to indicate data type
Double – numeric data type that possibly contains decimals
Reserves a space in the computer’s memory for a value
Numeric variables are given the value of zero initially

4. VARIABLE ASSIGNMENT
Variables are given values through assignment statements
Identifier (variable name) is on the left of the = and the value on the right
Example: dblRadius = 12.3
The value of 12.3 is stored in the memory location named dblRadius
You cannot reverse an assignment statement: = dblRadius ‘Error!

5. VARIABLE ASSIGNMENT
An expression can be used on the right side of an assignment statement
Example: dblArea = 3.14 * dblRadius ^ 2
The result of the expression will be stored in the memory location named dblArea
Variables can be used wherever a value is used

6. VARIABLE ASSIGNMENT Variables can only store one value at a time
Example: DIM dblY As Double
dblY = 5
dblY = 10.5
The value of 10.5 is stored in dblY because it was the last value assigned

7. VARIABLE ASSIGNMENT
Expression on the right side of the = and then the resulting value is given to the variable on the left side.
Example: DIM dblAdd As Double
dblAdd = 5
dblAdd =dblAdd + 10
The value of 15 is stored in the memory location dblAdd

8. LAB TIME
Review # 1
Review #2

9. In review 1 part (b), what would be the final value of dblResult if the statement dblResult = 5 was removed?
Write a comparison of the readability of the Circle application from Chapter Three Review #8 to the Circle Area application of Chapter Four Review #2.