.what is the answer for this question?

Dear Student

First of all solve 
10²³/10²⁴ = 1/10 [23 zero's on numerator cancel out 23 zeros in denominator].

Now it becomes, 
1.66 x 6.023 /10
= 166 x 6.023 
100 x 10 x 1000

= 999818
1000000

= 0.999818

Regards