2 7x10 7 July 8, 2019 16 32 64 128 2 7 x 10 7 7 x 2 )= 7x 10 7 x 2 10 7x 4 7.0 x 10 7 2 7 1 2 x 7 10 2 7x10 2 7×107 2 7×10 7 x 10