To write 42.8181 as a fraction you have to write 42.8181 as numerator and put 1 as the denominator. Now you multiply numerator and denominator by 10 as long as you get in numerator the whole number.
42.8181 = 42.8181/1 = 428.181/10 = 4281.81/100 = 42818.1/1000 = 428181/10000
so the answer is 428181/10000