VARIABLE COST IS SAID TO BE VARIABLE BECOZ IT VARIES WITH 
CHANGE IN THE NUMBER OF THE UNITS.IT ALWAYS FLUCTUATES

variable cost depends upon the production means it will 
change according to the production of no of units. if the 
production of units will increase the cost will be 
increased, if the production of units will decrease the 
cost will be decreased. it is in fluctuate in nature.

The variable cost will always various according to the no. 
of Units produced hence it is said to be variable

Cost that varies according to output is called Variable 
cost, if Output increases variable cost increases and Vice-
versa, But variable cost will fixed per unit of output upto 
some range, variable cost is also called as marginal cost.

Variable cost  is  a  fluctuating cost.it varies  according to
number of unit produced.
if no of unit increased variable cost also increases
if no of unit decreased variable cost also decreases.

Variable cost is the cost which increas od decrease with 
the scale of production. It doesn't depend on the no of 
units, there will be effect of economies to the scale i.e. 
increase or dectrease..