Biology I / From Single Cells to Multicellular Bodies
Practice question · Estimate

An adult human has roughly 101310^{13} cells, all descended from one fertilised egg. Set the approximate number of successive doublings this represents.

Estimate on a scale from None (0) to 100 doublings (100).

Hints
  1. Each doubling multiplies the count by two, so ask what power of 2 reaches 10 to the 13.
  2. Since 2 to the 10 is about 1000, three such blocks give 10 to the 9; you need a little over four.
Show the answer

43 (answers within ±4 count)

Why

Because 2101032^{10} \approx 10^3, reaching 101310^{13} needs about 13/0.3014313/0.301 \approx 43 doublings. Exponential growth covers an enormous range in remarkably few steps, which is also why uncontrolled division is so dangerous.

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