Here is a simple QBASIC Program on how to display the square of 7 using a subroutine function.
SOLUTION:
SUB DisplaySquare(n)
DIM square AS INTEGER
square = n * n
PRINT "The square of "; n; " is "; square
END SUB
CALL DisplaySquare(7)
OUTPUT:
The square of 7 is 49
EXPLANATION:
SUB DisplaySquare(n): defines a subroutine named DisplaySquare that takes one parameter n
DIM square AS INTEGER: It declares a variable square to store the result of the multiplication.
square = n * n: This line calculates the square of n and stores it in the square variable.
CALL DisplaySquare(7): This line calls the DisplaySquare subroutine with the argument 7.
And this is how you can use subroutine to display the square of 7.