To write 16 as a decimal, you simply write "16.0" or "16.00". This is because whole numbers can be represented as decimals by adding a decimal point and zero after the number. In this case, the number 16 remains the same when written as a decimal.
A decimal number is simply a way of representing a number in
such a way that the place value of each digit is ten times that of
the digit to its right. A decimal representation does not require a
decimal point. So the required decimal representation is 16,
exactly as in the question.