calculator.
you can think of a calculator as an infinite sequence of symbols, where the nth
symbol is the nth button you clicked. You do NOT store the full sequence since when you incorporate
operators you are really doing evaluations 
so 
2+*3=4+5 is equivalent to 
2*3, display,  (delete saved symbols)
4+5
and 2+3/4 is equivalent to
2+3 (display and store 5, delete other symbols)
5/4, display and store result. (chaining)

initialize:
two number boxes  num1 num2 to 0; (note, always display num1, our computations are to be stored here).

first operand entered  during current formula=false
operator entered  in current formula=false
second operand (number2)entered in current=false

enable_number1_mod=true (when this is disabled, number2 is enabled by default
mod here refers to concatenation)

equals_just_entered=true;// imagine you hit = when you open your calculator.
						// it should be doing nothing, right?

(nonequals) arithm operator value="+";(because 0+0=0, good initial choice).

input: button
// +2 is really equivalent to 0+2;
if button is arithm operator{
	if equals_just_entered{
		second_operand_entered=false;
	}
	else if arithm op.already previously entered in current formula
		if number2 already entered in current formula{
			compute number(operator value)number2
			store result in number1
			second_operand_entered= false (note, not the operator flag)}
	operator_value = button;
	enable_number1_mod=false;
	equals_just_entered=false;
	}
else (has to be =)
	if you have entered number2 in current formula
		number1=number1(op)number2
	else
		number1=number1 op number1
	equals_just_entered=true;
first_operand_entered=true;
 
why do we need the equals_just_entered flag? because we know that if we hit a number after an =,
the whole problem is reset
example
2x3===4+5+6==1 (is what?)
note that if i do
2x3=+4 it DOESNT reset the calculator.
this comes into play in the other big case: digits

input: digit
 if equals_just_entered:
	reset the  global variables (this will start a new formula)
	num1=digit;
else if (enable_number1_mod)
		concatenate to number1
else if (second_operand entered_)
		concatenate to number2
else	number2=digit;
		second_operand_entered=true;
equals_just_entered=false;//FOR ALL CASES HERE	




array1=document.getElementsByTagName("p");
node_max=array1[0];

for(i=0;i<array1.length;i++){
if(array1[i].innerHTML.length>node_max.innerHTML.length);
	node_max=array1[i];
}
alert(node_max.innerHTML);
arrayimg=document.getElementsByTagName("img");
for(i=0;i<array1.length;i++){
arrayimg[i].id="img"+String(i);
}