A circular disc of area 0.49 π square meters, rolls

A circular disc of area 0.49 π square meters, rolls down a length of 1.76 km. The number of revolutions it makes is ?

Area = πr² = 0.49π
⇒ r = 0.7 m

Number of revolutions = total distance / circumference
= (1.76 x 1000) / (2 x 22/7 x 0.7)
= 400