\(\frac{0.21 \times 0.072 \times 0.00054}{0.006 \times 1.68 \times 0.063}\)

= \(\frac{9 \times 10^{-10}}{7 \times 10^{-8}}\)

= \(1.2857 \times 10^{-2}\)

= \(0.012857 \approxeq 0.01286\) (to 4 s.f)