1 hour = 3600 s
1 day = 24 hours = 24 x 3600 = 86400 seconds
1 day ...... 86400 seconds
365 days ..... t seconds
t= 365 x 86400 /1 = 31536000
So, we have 31536000 seconds in 365 days. => 31536000 seconds = 1 year
--------------------------------------------------------------
1 year ........ 31536000 seconds
15 years .......... z seconds
z = 15 x 31536000 / 1
z= 473040000
So, 15 years = 473040000 seconds !!!!!!
Done.
