89^2 = (90-1)^2= 90^2-2*90*1-1= 8100-180+1=7921
38^2 =(40-2)^2=1600-160+4=1444
198^2= (200-2)^2=40000-800+4= 39204
89^2 = (90-1)^2= 90^2-2*90*1-1= 8100-180+1=7921
38^2 =(40-2)^2=1600-160+4=1444
198^2= (200-2)^2=40000-800+4= 39204