[ ( j - 25 ) * 64 - 12 ] : 4 : 5 = 25
[ ( j - 25 ) * 64 -12 ] : 4 = 25 * 5
[ ( j - 25 ) * 64 - 12 ] : 4 = 125
[ ( j -25 ) * 64 - 12 ] = 125 * 4
(j - 25 ) * 64 - 12 = 500
( j - 25 ) * 64 = 500 + 12
( j - 25 ) * 64 = 512
64 j - 1600 = 512
64 j = 512 + 1600
64 j = 2112
j = 2112 : 64
j = 33