12 years is 378,683,112 seconds.
20x365.25x24x60x60=631152000 seconds
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
31556926 in a year x 14 years =441796964 seconds
12 years is 378,683,112 seconds.
47 years = 1,482,192,000 seconds
72 years is about 2,272,098,672 seconds.
283824000 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.
20x365.25x24x60x60=631152000 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?
94,670,778 seconds.