clc
//
//
//

//Variable declaration
n=59                 //no. of ring
lambdaa=6*10**-7     //Wavelength
R=0.9                //Radius
    
//Calculations
D59=sqrt(4*R*n*lambdaa)*10**2

//Result
printf("\n The Diameter of the nth dark ring is %0.3f cm",D59)