The CAS Registry Mumber 827-06-5 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 8,2 and 7 respectively; the second part has 2 digits, 0 and 6 respectively. Calculate Digit Verification of CAS Registry Number 827-06: (5*8)+(4*2)+(3*7)+(2*0)+(1*6)=75 75 % 10 = 5 So 827-06-5 is a valid CAS Registry Number.