Rather than giving you a one shot answer, I'm encouraging you to learn how to do unit conversions. The basic conversion is 1 inch = 2.54 centimeters exactly. So now you can write two different forms of "1"
First, (1 inch)/(2.54 cm) = 1, and (2.54 cm)/1(inch) = 1. Next, whenever you multiply some "thing" by 1 you haven't changed the "thing". Which form of 1 do you use? Use the form that has puts the new unit in the numerator and the old unit in the denominator. Then multiply. I'll use a "thing" different from your specific number: 13.75 inches.
13.75 inches X (2.54 cm)/(1 inch) = 34.925 cm. inches/inch. But inches/inch = 1, so we have 34.925 cm. Now try it out on your own number and see if these other guys are telling the truth. :)
If you learn this technique, you can do all the conversions you want given 1 basic relationship.
The average fully grown banana is about 8 inches long, so you would you inches as a unit of measurement or centimetres, 8 inches is about 20 centimetres.
1 inch = 2.54 cm 8 inches * 2.54 cm/1 inch = 20.32 cm
80 inches = 203.2 cm
9.5 centimeters is 3.74 inches.
8 inches=20.32 centimeters