A membrane phospholipid exchanges places with a neighbour about $10^7$ times per second, but flips between leaflets about once per hour. How many times faster is lateral exchange than flipping, given an hour is 3600 s? Give the answer as a power of ten.

10.6 (answers within ±0.4 count)

Lateral exchange happens $10^7 \times 3600 = 3.6 \times 10^{10}$ times an hour against a single flip, roughly $10^{10.6}$ times faster. Flipping is so rare because it drags a hydrophilic head through the hydrophobic core, and cells use dedicated flippase enzymes when they need it done.