0.42.......2 numbers in the decimal side
3.8.........1 number in the decimal side
10.51.....2 numbers in the decimal side
so u have a total of 5 numbers in the decimal side...so there are 5 decimal places in the product
check..
0.42 * 3.8 * 10.51 = 16.77396...(correct)...5 decimal places