 For if the algorithm requires "N" steps, then "b" is greater than or equal to "F""N"+1 which in turn is greater than or equal to "φ""N"−1, where "φ" is the golden ratio.Since "b" ≥ "φ""N"−1, then "N" − 1 ≤ log"φ""b".Since log10"φ" > 1/5, ("N" − 1)/5 10"φ" log"φ""b" = log10"b".