As of January​ 2016, the national debt of a certain country was ​$18.8 trillion. a. Express 18.8 trillion in scientific notation. b. Four years of​ tuition, fees, and room and board at a public college cost approximately ​$50 comma 000. Express this number in scientific notation. c. Use your answers from parts​ (a) and​ (b) to determine how many citizens could receive a free college education for ​$18.8 trillion.