(am)n=amn

(ab)m=ambm

The number in it represents the number of times, which is the one marked with superscript.

(a+b)(a-b)=a2-b2

(a+b)2=a2+b2+2ab

(a-b)2=a2+b2-2ab

The numbers in these three represent squares, but Baidu can't type squares.