I have been having trouble with these seemingly simple problems. I am able to solve till the point it is 10^(-3)*2^(-6). I get that there are atleast three zeroes after the decimal because of the 1/1000 but how do we deduce 2^(-6)? Any help is highly appreciated, thanks!

Thanks, did you use a calculator for 1/64? @manalimodi48

No I didnt.

Another way could be the number of zeros in 1/x is k-1, where k is the number of digits in x.

If x is a power of 10, then the number of digits in 1/x will be k-2.

But I think calculating is the best way as it gives confidence!!