(a) Without using tables, find the value of \(\frac{0.45 \times 0.91}{0.0117}\)

(b) Find the number which is exactly halfway between \(1\frac{6}{7}\) and \(2\frac{11}{28}\).

(c) If each interior angle of a regular polygon is five times the exterior angle, how many sides has the polygon?

(d) Calculate the volume of the material used in making a pipe 20cm long, with an internal diameter 6cm and external diameter 8cm. [Take \(pi = \frac{22}{7}\)].