At the second store, she tried on 7+2=<<7+2=9>>9 pairs of shoes.
Therefore, at the first three stores, she tried on 7+9+0=<<7+9+0=16>>16 pairs of shoes.
At the fourth store, she tried on 16*2=<<16*2=32>>32 pairs of shoes.
Thus, in total, she tried on 16+32=<<16+32=48>>48 pairs of shoes.
#### 48