Chapter 7 - Numbers

Computers are very good at math. Let's get the computer to do some math for us. Here's a simple multiplication calculator:

     CLS
     INPUT "Enter the first number: ", A
     INPUT "Enter the second number: ", B
     PRINT "The answer is: "; A * B

If you have trouble finding the star (or asterisk "*") on the keyboard, it is usually above the number 8. Run it, and enter two numbers. It does an excellent job multiplying for you.

Variables and Math

A and B are variables, just like Name$. Unlike Name$, A and B do not have a dollar-sign after their names. This is because they are only holding numbers, not letters.

Star

"A * B" means "A times B". QBASIC doesn't use "X" for multiplication because you might want to have a variable called "X".

What else?

Try changing the "A * B" to "A - B" for subtraction. "A + B" will do addition, and "A / B" will do division. Why "/" for division? Because there's no division sign key on the keyboard. At least I haven't found one.

Expressions

"A * B", "A + B", "A - B", and "A / B" are called mathematical expressions, or simply "expressions".

Learned

• Variables with numbers
• INPUT with numbers
• Multiplication, Division, Addition, Subtraction
• Expressions