The CAS Registry Mumber 1251864-86-4 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,2,5,1,8,6 and 4 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 1251864-86: (9*1)+(8*2)+(7*5)+(6*1)+(5*8)+(4*6)+(3*4)+(2*8)+(1*6)=164 164 % 10 = 4 So 1251864-86-4 is a valid CAS Registry Number.