The CAS Registry Mumber 58350-71-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,8,3,5 and 0 respectively; the second part has 2 digits, 7 and 1 respectively. Calculate Digit Verification of CAS Registry Number 58350-71: (7*5)+(6*8)+(5*3)+(4*5)+(3*0)+(2*7)+(1*1)=133 133 % 10 = 3 So 58350-71-3 is a valid CAS Registry Number.