вычислить квадрат числа
(1/4)^2=(1/4)*(1/4)=1/16
(3/8)^2=9/64
(5/6)^2=25/36
(2/7)^2=4/49
(1 1/2)^2=(3/2)^2=9/4=2 1/4
(4 1/9)^2=(37/9)^2=1369/81= 16 73/81
(6 2/3)^2=(20/3)^2=400/9= 44 4/9
