Why was Qutub-ud- Aibak given the title of 'Lakh Baksh'?

Qutubuddin Aibak gradually rose to the rank of a Commander and became a trusted slave of Sultan Ghori. The conquests of northern India were executed mainly by Qutb-ud-din Aibak, which helped Ghori to consolidate his position there. Gradually, as Sultan Ghori concentrated on Central Asia after 1192, he was given the independent charge of the conquests in India. Qutb-ud-din Aibak gave large sums of money in charity, thus earning the name LAKH BAKSH or giver of lakhs.