How many seconds....?

Ewan completed some additional homework this week.  He has worked out how many seconds there are in:

One year - 4,492,800

Twenty years - 89,856,000

Forty years - 179,712,000

Sixty years - 269,568,000

Can you work out how Ewan knows this?

What calculations did he have to do?

Is he correct with his answers?

Leave a comment to let us know the answers to any of the questions above.