arithmetic functions 1

created file and comments
arithmetic function 2

added function
arithmetic lesson 2

tested functions adding modules
arithmetic lesson 4

added modulus, no bugs
arithmetic lesson functions

added if statements, validated output
arithmetic functions 2

added error for attempts to divied by zero
arithmetic revised
arithmetic vr 2

cleaned up divide error
arithmetic lesson

added print value of args
arithmetic lesson

added function to validate
arithmetic returns

added returns no errors, moving to divid 0 return false
arithmetic functions return complete

completed returns, no echo statements