21 inches into cm if cm is =2.5 show working

To convert inches to centimeters, you can use the conversion factor:

1 inch = 2.54 centimeters

So, to convert 21 inches into centimeters:

21 inches * 2.54 cm/inch = 53.34 cm

If cm is actually 2.5, we can check this by using the same conversion factor:

21 inches * 2.54 cm/inch = 53.34 cm

Since 53.34 cm is not equal to 2.5 cm, it seems there was a mistake in the given information.