The Fibonacci sequence is defined by the recurrence relation:
Fn = Fn-1 + Fn-2, where F1 = 1 and F2 = 1.
Hence the first 12 terms will be:
F1 = 1
F2 = 1
F3 = 2
F4 = 3
F5 = 5
F6 = 8
F7 = 13
F8 = 21
F9 = 34
F10 = 55
F11 = 89
F12 = 144
The 12th term, F12, is the first term to contain three digits.
What is the first term in the Fibonacci sequence to contain 1000 digits?
Sub Euler25() Dim Fcurr As String, Fnext As String, I As Integer, ProcTime As Single ProcTime = Timer Fcurr = 1: Fnext = 1: I = 2 Do Dim Fnew As String Fnew = LargeAdd(Fcurr, Fnext) Fcurr = Fnext: Fnext = Fnew I = I + 1 Loop Until Len(Fnew) >= 1000 Debug.Print I, Timer - ProcTime End Sub