% Expansion = Total expansion/ Length of test piece x 100
If expansion from 20C to 500C = 0.418%
( 0.418/100) * (1/480) = 8.7 x 10-6
Then coefficient of expansion = 8.7 x 10-6
Note: %expansion and coefficient of expansion should always be
quoted with reference to the temperature range over which they
were measured.