The prime factors are 2, 4, 8
Irrational numbers are numbers that can not be written as a simple fraction. An example of one would be 
. Pi is about 3.14, but it goes on forever. You can not write pi as a simple fraction.
4.19% = .0419
When percent to decimal, move the decimal two to the left.
When decimal to percent, move the decimal two to the right. Good luck!
The answer for this is 2b-18
