How many seconds old will someone be at the very moment they turn 10 years old?

Hint: According to the question, we have to find the numbers of seconds old will someone be at the very moment they turn 10 years old.
So, first of all we have to understand that it is depending on the number of leap years, which can be 2 or 3 during 10 years.
So, first of all we have to find the numbers of seconds in one year by using the concept as mentioned below.
Numbers of second in one year:
$ \Rightarrow \text{Year} \to \text{Days} \to \text{Hour} \to \text{Minutes} \to \text{Seconds}$ -------(A)
Now, we have to find the numbers of seconds in 10 years by multiplying the numbers of seconds in one year to 10.
Now, we have to calculate the number of seconds in 2 or leap years also.

Complete step by step answer:
Step 1:
First of all we cannot give an absolute exact answer without knowing the date and year of birth, because of the effect of leap year.
So, let’s ignore the leap year for now and find the number of seconds in a year by using concept (A) as mentioned in the solution hint.
$ \Rightarrow 1 \times 365 \times 24 \times 60 \times 60$
$ \Rightarrow 31536000$

Step 2:
Now, we have to find the number of years in 10 years as mentioned below.
Number of years in 10 years $=$ Number of years in 1 year $\times$ 10
$ \Rightarrow 31536000 \times 10$
$ \Rightarrow 315360000$

Step 3:
Now, we have to calculate the number of seconds in one day as mentioned below.
Number of seconds in one day = $24 \times 60 \times 60$
$ \Rightarrow 86000$
Now, we include 2 leap years,
$ \Rightarrow 315360000 + 2 \times \left( {86000} \right) = 315532800$
Step 4: Now, we include 2 leap years,
$ \Rightarrow 315360000 + 3 \times \left( {86000} \right) = 315618800$
Final solution: Hence, the number of seconds old will be someone at the very moment they turn 10 years old either $315532800$ or $315618800$.

Note:
- It is necessary to understand that the number of seconds depends on the number of leap years, which can be 2 or 3 during 10 years.
- It is necessary to find the number of seconds in 1 year using the concept as given in the solution hint.