The CAS Registry Mumber 2018-86-2 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,0,1 and 8 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 2018-86: (6*2)+(5*0)+(4*1)+(3*8)+(2*8)+(1*6)=62 62 % 10 = 2 So 2018-86-2 is a valid CAS Registry Number.