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The Fibonacci sequence is defined by the recurrence relation:

F_{n}= F_{n-1}+ F_{n-2}, where F_{1}= 1 and F_{2}= 1.

Hence the first 12 terms will be:

F_{1}= 1

F_{2}= 1

F_{3}= 2

F_{4}= 3

F_{5}= 5

F_{6}= 8

F_{7}= 13

F_{8}= 21

F_{9}= 34

F_{10}= 55

F_{11}= 89

F_{12}= 144

The 12th term, F_{12},
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