The CAS Registry Mumber 58155-82-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,8,1,5 and 5 respectively; the second part has 2 digits, 8 and 2 respectively. Calculate Digit Verification of CAS Registry Number 58155-82: (7*5)+(6*8)+(5*1)+(4*5)+(3*5)+(2*8)+(1*2)=141 141 % 10 = 1 So 58155-82-1 is a valid CAS Registry Number.