47 years = 1,482,192,000 seconds
72 years is about 2,272,098,672 seconds.
12 years is 378,683,112 seconds.
25 years is 788,923,150 seconds.
Since there are 86,400 seconds in a day and 365.25 days in a year, a 9-year old has lived at least 284,018,400 seconds.
A minimum of 504,576,000 seconds but it depends on the time of day you were born and how many leap years you have lived through.
A 9 year old will have lived through at least 2 leap years, so allowing for that, they will have been alive for 283,996,800 seconds. It is possible they have lived through 3 leap years in which case they will have been alive for 284,083,200 seconds.
at least 1,226,227,704 seconds = 60 seconds x 60 minutes x 24 hours x 365.242199 days x 40 years
The answer depends on your 13 year old what! And what has your 13 year old possession got to do with your age, anyway?
34.2 years is about 1,079,246,869.2 seconds.