A laboratory measurement finds 165 mg of hemoglobin per mL of blood. Hemoglobin has a molecular weight of 64 kDa or 64,000 u, where 1 dalton (Da) = 1 atomic mass unit (u) = 1.66 * 10 ^ - 24 g. Estimate the number of hemoglobin proteins in one red blood cell Round your answer to the nearest billion .