To write 3.88888 as a fraction you have to write 3.88888 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.
3.88888 = 3.88888/1 = 38.8888/10 = 388.888/100 = 3888.88/1000 = 38888.8/10000 = 388888/100000
And finally we have:
3.88888 as a fraction equals 388888/100000