Bit of a techy one, but if you import data into a spreadsheet from a unix database (mysql for example) it might have 'timestamp' fields. This is the number of seconds since 1st January 1970. To convert it to a date in your spreadsheet, divide by the number of seconds in a day (86400) then add 1st January 1970 (25569) for example a formula would be =(A1/86400)+25569

Bit of a techy one, but if you import data into a spreadsheet from a unix database (mysql for example) it might have 'timestamp' fields. This is the number of seconds since 1st January 1970. To convert it to a date in your spreadsheet, divide by the number of seconds in a day (86400) then add 1st January 1970 (25569) for example a formula would be =(A1/86400)+25569