how many seconds are in 60,4657 years

In a year there are 365 days and in a day there are 24 hrs .In an hour, there are 60 minutes and in a minute there are 60 seconds. 

Thus in a year no seconds = 365×24×60×60 = 31536000

Thus in 604657 yrs, number of seconds = 604657 × 31536000

Multiply and you will get the answer.

The figures given in the question are very large and out of the scope of a class 4 student.