The CAS Registry Mumber 58718-78-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,8,7,1 and 8 respectively; the second part has 2 digits, 7 and 8 respectively. Calculate Digit Verification of CAS Registry Number 58718-78: (7*5)+(6*8)+(5*7)+(4*1)+(3*8)+(2*7)+(1*8)=168 168 % 10 = 8 So 58718-78-8 is a valid CAS Registry Number.