Fibonacci Sequence

Challenge

Write a program to find the index of the first term in the Fibonacci sequence to contain 10 digits?

For this problem, you will have to write two functions:

1. countdigits ( )

This function takes an integer and returns the number of digits in that integer.

2. printNumberandIndex ( )

This function creates a Fibonacci sequence and checks whether the latest number generated in the sequence has 10 digits using the countdigits() method.

Example

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.

Coding exercise

Try to solve this challenge on your own. If you can’t solve it, you can look at the solution and explanation below.