Polish Notation

A way of expressing 

a

 sequence of calculations without using 

parentheses

 to 

show

 which operation must be performed first.For example, the expression 2(4+5), which instructs the reader to add 4 + 5 

and

 multiply by 2, would be written 

*

 2 + 4 5 

in

 Polish notation.To 

make

 the calculation, 

read

 from right to left until you find an operation, then perform the operation on the numbers immediately to the right of 

it

, 

and

 continue to the 

next

 operation.So 

*

 2 + 4 5 becomes 

*

 2 9 

and

 then 18.