The average eukaryotic cell is about 100 μm (100 x 10^-6 m. = 10^-4 m.) long.

You have 200 trillion (2 x 10¹⁴) somatic cells (p. 230).

Total length of your cells lined up end-to-end: (2 x 10¹⁴) x (10^-4 m.) = 2 x 10¹⁰ m. = 2 x 10⁷ km.

The earth's circumference is 40 million m. (40 x 10⁶ m. = 4 x 10⁷ m. = 4 x 10⁴ km.

2 x 10⁷ km. / 4 x 10⁴ km. = 500: your cells can wrap around the earth 500 times.