To find the length in centimeters equivalent to 30 inches, we can use the conversion factor between inches and centimeters. The relationship is given by:
1 inch = 2.54 centimeters.
Using this conversion, we can calculate the length in centimeters for 30 inches as follows:
\[ 30 \text{ inches} \times 2.54 \text{ centimeters/inch} = 76.2 \text{ centimeters} \]
Therefore, the missing number in the last row of the table for 30 inches is 76.2 centimeters.