how many seconds are there in a year?

Well...

There are 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day, and 365 days in a year (366 if it's a leap year).

Regular years: 60 * 60 * 24 * 365 = 31,536,000 seconds.

Leap years: 60 * 60 * 24 * 366 = 31,622,400 seconds.