[tex]a)~98^2-2^2= (98-2)(98+2)=96 \times 100=\boxed{9600} \\
b)~994^2-6^2=(994-6)(994+6)=988 \times 1000=\boxed{998000} \\
c)~93 \times 107=(100-7)(100+7)=100^2-7^2 = 10000-49 =\boxed{9951} \\
d)~192*208= (200-8)(200+8)=200^2-8^2= 40000-64=\boxed{39936}[/tex]