Question 1
A decimal number is a modified way of expressing a fraction. A fraction shows a number as a part of a whole figure. For example, 2/3 means when a quantity is divided into 3 equal parts we have to take 2 parts of it. When this fraction is expressed in terms of fractions of 10, 100, 100 it becomes a decimal fraction. For example we can write 2/5 as 4/10. Thus 4/10 is decimal fraction. We can write 4/10 as 0.4 . This is a decimal number. In a similar way we can write 13 9/100 as 13.09.
Question 2
PEMDAS stands ...