Consider a function which, for a given whole number n, returns the number of ones required when writing out all numbers between 0 and n. For example, f(13)=6. Notice that f(1)=1. What is the next largest n such that f(n)=n?

2 Answers on this Question

1. #1: N = 1, f(N) = 1
   #2: N = 199981, f(N) = 199981
   #3: N = 199982, f(N) = 199982
   #4: N = 199983, f(N) = 199983
   #5: N = 199984, f(N) = 199984
   #6: N = 199985, f(N) = 199985
   #7: N = 199986, f(N) = 199986
   #8: N = 199987, f(N) = 199987
   #9: N = 199988, f(N) = 199988
   #10: N = 199989, f(N) = 199989
   #11: N = 199990, f(N) = 199990
   #12: N = 200000, f(N) = 200000
   #13: N = 200001, f(N) = 200001
   #14: N = 1599981, f(N) = 1599981
   #15: N = 1599982, f(N) = 1599982

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2. Next Largest NO such that f(n) = n is
   199981

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