The problem is to work out the first Fibonacci number that is 1000 digits long. I have calculated all the numbers up to f1000 = f999+f998 using a spreadsheet but there doesn't seem to be a pattern. Sometimes it takes 5 goes to get another digit in the answer sometimes it takes 4.
It seemed there was a pattern emerging as in it would take 3 5's and then a 4 (19 turns for example f21 - f40 would be an increase of 4 digits 5 , 5, 5, 4) then 2 lots of 4 5's then a 4 followed by another 4 5's then a 4. However f308 to f337 took 5 5's then a 4 ie 29 moves and f337 to 351took only 2 5's then a 4 (14 turns)
it also doesn't follow the pattern of 19 followed by 2 24's at f174 to f217 ( 19 24 19 instead of 19 24 24) it does this again at f619 - f682.
all this to say am i thrashing around on a wild goose chase and there is a type that will handle numbers of that size or something i can use with strings instead
