Simplify the following text for a Grade 11 native English-speaking person.
Original: RÃ ikkÃ nen is known to be very relaxed , calm , cool , and calculating in his everyday life as well as in his racing careerâ '' prompting the nickname `` Iceman '' , which RÃ ikkÃ nen has tattooed on the underside of his left forearm and which is also subtly written on the side of his current helmet design .
Simplified: RÃ ikkÃ nen is very calm , cool , and calculating in his race strategyâ '' prompting the nickname `` Iceman '' , which is subtly written on the side of his current helmet design .