Given :
Average mass of the cell = 10 X mass of bacterium.
Number of cell= Â (Mass of humming bird)/ (mass of the cell@)
a) The mass of a hummingbird is  , while the mass of a cell is  . The number of cells in the hummingbird is
          〖10〗^(-2)/〖10 X 10〗^(-15) = 〖10〗^12  cells
Number of cells in humming bird = 1012 cells
b) The mass of a person is  .
          (〖10〗^2  kg)/(10 X 〖10〗^(-15) )= 〖10〗^16  cells
Number of cells in human = 1016 cells