Laravel request digit position of an word per login session

It is possible in laravel to find an position from an digit in an word and make it random?

Example

Secret Word= haveaniceday

Laravel request now for example the last digit from word where y:

Whats the 12th digit from your word? Enter in text field

If i enter y and its true i redirect.

I have try it with strpos but they cant choose always an new digit per Session.

Any idea?

via Chebli Mohamed