When young children attempt to locate the positions of numerals on a number line, the positions are often logarithmically rather than linearly distributed. This finding has been taken as evidence that the children represent numbers on a mental number line that is logarithmically calibrated. This article reports a statistical simulation showing that log-like positioning is a consequence of 2 factors: the bounded nature of the number line and greater uncertainty about the meaning of the larger, less frequent number words. Two experiments likewise show that even college students produce log-like placements under the same 2 conditions. In Experiment 1, participants identified positions on a number line for a set that included both conventional and fictitious numbers (e.g., a zillion). In Experiment 2, participants did the same for conventional numbers that included some larger, unfamiliar items (e.g., a nonillion). Both experiments produced results better fit by logarithmic than by linear functions.