CareerCup

See if this is correct
Every year the amount will double.
So (log(richest person amount)base2) + 1

53B according to Forbes,

10 yrs -> 1 K
20 yrs -> 1 M
30 yrs -> 1 B
you need another 6 years to pass 56B.

that's a total of 36 years

Heh heh ... not bad I got 37 years before reading this thread, we're all roughly in the same ballpark.

Make sure the richest man also has not invested in the same bank :P

suppose the richest has 40B$, it takes about 48 years. am I right?

Seems like a horrible question for a programming job.

never coz i am not the only customer of that bank

I bet the thing they're trying to find here is if you know what 2^32 is. What I'd say in an interview is:
"Well, I don't know precisely how much money the richest guy has, but it's in the 2-digit billions.
I know 2^32 is 4.3 billion, *2 is 8.6 *2 is 17.2 *2 is 34 *2 is 68 and change, so probably circa 36.

a=1
b=0
while(a<rich_amount)
      {
        a=2*a;
        b++;
      }
printf("no of yrs %d",b);

Hey, you need 'ye' 30/36/40/42/48 whatever years to cross today's richest man. That's unfair because you never know how much wealth today's richest man can gather in the next 'ye' years.......... You cannot compare x and y, where x is present value and y is the value 'ye' years from now. Need to take the present value of y...(discounting it with risk free interest)
So, answer if you find X money after ye years, discount it by 6% for 'ye' years... That way you need few more years.....

Never
No bank will open your account or any business contract in 1$

That only I can ans for this UNIQUE qus..!! :)