6. There are 99 bags, each containing $1,2,3,4, \cdots \cdots, 99$ gold coins respectively. Each time the fairy wields her magic wand over some of the bags, the number of gold coins in these bags increases by the same amount. To make the number of gold coins in each bag exactly 100, the fairy needs to wield her magic wand at least $\qquad$ times.
$7$