Evaluate and simplify tan 15º.

Tan (15) = tan (45 - 30)

= [tan (45) - tan (30) ] / [ 1 + tan (30) tan (45) ]

= (1 - 1/sqrt (3)) / (1 + 1/sqrt (3))

= (sqrt (3) - 1) / (sqrt (3) + 1)

= (sqrt (3) - 1) ^2 / (3 - 1)

= 1/2 [3 + 1 - 2sqrt (3) ]

= (2 - sqrt (3))

= 0.27 is your answer