The CAS Registry Mumber 77486-34-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,4,8 and 6 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 77486-34: (7*7)+(6*7)+(5*4)+(4*8)+(3*6)+(2*3)+(1*4)=171 171 % 10 = 1 So 77486-34-1 is a valid CAS Registry Number.