21 3 x 7 ) 9 July 8, 2019 16 32 64 128 21 3 x 7 )+ 9 21 7 3 х 9 21 3 7 2x )= 5 2 x 9 3 3x 7 )= 9x 21 2 x 3 7 9 21 8 21 x 7 9 x 3 4 16 21 7 x 3 9 7 9 x 3 21 simplified 7 x 9 )+ 21 x 3 )= 406 3 7 x 5 9 x 21 5