Estimate the number of cells in a(n) 74-kilogram (163-pound) person, assuming the human body is 100% water (actually it is 60-70% water) and that 1 liter of water weighs 1 kilogram. cells per person
The average cell in the human body weighs about 1 nonogram [10^-9 grams]. Or 1 gram =10^9 cells.
So, 74 kilograms x 1,000 grams x 10^9 cells =74 x 10^12 cells. But, because there are dozens of different types of cell in the human body, the actual number is about 1/2 the above figure or about 37 x 10^12 cells.