More than any other number in your chart, your Expression number reflects who you are as a whole person on a deep level (rather than the "face" you show to the world, described by your Personality number). 

It cannot be over-emphasized how important it is to recognize that the same number in a different area of your chart will affect you differently. There may be times you read something that seems to directly contradict an earlier statement. Yet, if you take time to carefully think about the opposing information you might recognize that, being the complex individual you are, you carry the same contradictions. This is natural and true for all of us. You may excel at organization in one area of your life, while chaos rules in another. You may be tactful and sensitive in one setting, but direct and confrontational in another.

Be aware that it is more difficult to overcome negative traits you recognize in yourself when they are found in this part of the chart, than when they are found under the Life Path description.