How much calories does this club sandwich contain?

Question

it had ham, bacon, a piece of egg, lettuce and mayonnaise..

Answer 1

No way to know without details about the size and type of bread, the size and type of ham, the amount of mayo, etc.  With practice you can guesstimate the amount of calories for each component of a sandwich and add them up.  The one you're talking about could have maybe 300 to 500 cal. or more.