Use absolute references to refer to cells that you don't want to change as the formula is copied. References are relative by default, so you would have to type dollar signs, as shown at number 2 in the example, to change the reference type to absolute.
Imagine that you receive a package of discount entertainment coupons offering a 7 percent discount for video rentals, movies, and CDs. You wonder how much you could save in a month by using the discounts. You could use a formula to multiply those February expenses by 7 percent.
You could type the discount rate 0.07 in the empty cell D9 and then type a formula in cell D4, starting with =C4*. Then you would enter a dollar sign ($) and D to make an absolute reference to column D, and $9 to make an absolute reference to row 9. Your formula would multiply the value in cell C4 by the value in cell D9.
Next you would copy the formula from cell D4 to D5 by using the fill handle . As the formula is copied, the relative cell reference changes from C4 to C5, while the absolute reference to the discount in D9 does not change; it remains as $D$9 in each row it is copied to.
Now it's time to practice what you've learned in this lesson.