Answer:
40.2Ă—10^6 m ( this is in scientific notation )
4.02Ă—10^7 m (this is in standard form
Step-by-step explanation:
Radius of earth is 6400 km or 6400Ă— 1000 =6400000m =6.4Ă—10^6 m
circumference  C is given by formula C = 2πR WHERE C IS CIRCUMFERENCE AND R IS RADIUS
C = 2×π×6.4×10^6
C = 40.2Ă—10^6 m ( this is in scientific notation )
C= 4.02Ă—10^7 m (this is in standard form )