Ref. No. 41/1066
In the name of Allah the most gracious the most merciful
The answer to your question is as follows:
The extra reward of 100000 or 50000 for one fardh would be gained when performing Fardh Namaz in congregation in Haramain only and it will not be multiplied by 25 or 27 times. And if a person offers fardh namaz individually then he will not get the same reward as he gets in congregation.
And Allah knows best
Darul Uloom Waqf Deoband