Fibonacci

Today at Enrich the maths group did Fibonacci with spirals. The teacher asked if we know how it was related to Fibonacci and no one could guess why, so the teacher showed us the answer. We drew squares in a clockwise direction with the size of each square following the Fibonacci sequence. The fibonacci sequence goes: 1,1,2,3,5,8,13,21 and so on.  You find the next number by adding the previous 2 numbers together.  Do you know the fiftieth fibonacci number? Its twelve billion five hundred and eighty six million two hundred and sixty nine thousand and twenty five!