The CAS Registry Mumber 316142-61-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,1,6,1,4 and 2 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 316142-61: (8*3)+(7*1)+(6*6)+(5*1)+(4*4)+(3*2)+(2*6)+(1*1)=107 107 % 10 = 7 So 316142-61-7 is a valid CAS Registry Number.