The CAS Registry Mumber 78351-27-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,8,3,5 and 1 respectively; the second part has 2 digits, 2 and 7 respectively. Calculate Digit Verification of CAS Registry Number 78351-27: (7*7)+(6*8)+(5*3)+(4*5)+(3*1)+(2*2)+(1*7)=146 146 % 10 = 6 So 78351-27-6 is a valid CAS Registry Number.