The CAS Registry Mumber 86321-25-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,6,3,2 and 1 respectively; the second part has 2 digits, 2 and 5 respectively. Calculate Digit Verification of CAS Registry Number 86321-25: (7*8)+(6*6)+(5*3)+(4*2)+(3*1)+(2*2)+(1*5)=127 127 % 10 = 7 So 86321-25-7 is a valid CAS Registry Number.