The CAS Registry Mumber 77074-15-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,0,7 and 4 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 77074-15: (7*7)+(6*7)+(5*0)+(4*7)+(3*4)+(2*1)+(1*5)=138 138 % 10 = 8 So 77074-15-8 is a valid CAS Registry Number.