sr(18) = sr(9 x 2) = sr(9) x sr(2) = 3 x sr(2) = 4.24264068… This is a non-repeating decimal and therefore irrational (not able to be written as a fraction)
Every terminating decimal can be written as a fraction ie is rational. Example: 0.341 = 341/1000 Every repeating decimal can also be written as a fraction. Example 0.343434… = 34/99
