The CAS Registry Mumber 3951-01-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 3,9,5 and 1 respectively; the second part has 2 digits, 0 and 1 respectively. Calculate Digit Verification of CAS Registry Number 3951-01: (6*3)+(5*9)+(4*5)+(3*1)+(2*0)+(1*1)=87 87 % 10 = 7 So 3951-01-7 is a valid CAS Registry Number.