A code signal uses digit - letters - digit combinations but 0 and 1 are not used for either digits or letters . How many code signals are possible ?

A digital signal

A digital signal-

A digital signal-

A digital signal possess

An office manager must choose a five - digit lock code for the office door. The first and last digits of the code must be odd, and no repetition of digits is allowed. How many different lock codes are possible?