# ShareMyScreen/ProjectEuler/0025

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What is the index of the first Fibonacci number to have 1000 digits?

Admittedly, there are better ways of solving this using ^:_1 rather than having to up one's y until one hits upon the first 1000-digit one.

>: (i. 1e3"_) # @ ": "0 {{ (] , [: +/ (_1 _2)&{) ^: (y-2) (1x&, ^: 2)''}} 6e3 {{ (] , [: +/ (_1 _2)&{) ^: (y-2) (1x&, ^: 2)''}} NB. this explicit verb generates the first y Fibonacci series members, where y>=3 (1x&, ^: 2)'' NB. extended precision, because growth is rapid, begin by appending two 1s to nothing ] ^: (y-2) NB. because we have the first two members, y-2 sequent members are calculated (] , [: +/ (_1 _2)&{) NB. append the present series members to the sum of the last two # @ ": "0 NB. length of string of each of number >: (i. 1e3"_) NB. index of 1000 (represented as an infinite rank verb because that's how the train is); as site counts from 1, increment