представьте себе произведение в виде степени 0.25^7×1/64

0,25⁷ * 1/64 = (1/4)⁷ * (1/2)⁶ = ((1/2)²)⁷ * (1/2)⁶ =

= (1/2)²°⁷ * (1/2)⁶ = (1/2)¹⁴ * (1/2)⁶ = (1/2)¹⁴⁺⁶ = (1/2)²⁰