Question

$15$ years is how many seconds?

Answer 1

Hint:
Here we must know that we basically need to convert $15$ years into seconds. So we need to calculate the number of seconds in one year then multiply it by $15$ and get the answer. For this we can proceed by finding the number of seconds in one hour and then we will find the number of hours in one year and then accordingly use the unitary method to calculate the required value.

Complete step by step solution:
Here we need to find number of second that are there in $15{\text{ years}}$
Hence for this first of all we must know the number of seconds in one year. For this we must know the number of days in one year and also the number of seconds in one day. Therefore we need to proceed in a very clear way from the beginning till end.
Let us proceed by calculating first the number of hours in the year.
Number of days in one year$ = 365$
Number of hours in one day$ = 24$
As we know the number of hours in one days so we can easily calculate the number of hours in $365$ days which is one year:
Number of hours in one year$ = 365 \times 24$$ - - - - (1)$
Now we know that one hour has $60$ minutes
So if we will multiply this hours of one year got in equation (1) with $60$ we will get number of minutes in one year:
Number of minutes in one year$ = 365 \times 24 \times 60$$ - - - - (2)$
Now we know that one minute has $60$ seconds
So we have minutes of one year and hence if we will multiply that with $60$ we will get number of second in one year:
Number of seconds in one year$ = 365 \times 24 \times 60 \times 60$
So calculating this we will get:
Number of seconds in one year$ = 365 \times 24 \times 60 \times 60 = 31,536,000$$ - - - - (3)$
Now we need to calculate the number of seconds in $15{\text{ years}}$ so we need to multiply the equation (3) with $15$ we will get:
Number of seconds in one year$ = 365 \times 24 \times 60 \times 60 = 31,536,000 \times 15 = 473,040,000$ seconds

We can write it in the standard notation as $4.7304 \times {10^8}$ seconds

Note:
Here the student needs to remember all the relations between the units because without that these types of problems cannot be calculated. It is not just for the units of time but even for other units the same question can come to convert ${\text{kilograms to milligrams}}$ so proper knowledge of units is necessary.