The CAS Registry Mumber 1910-12-9 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,9,1 and 0 respectively; the second part has 2 digits, 1 and 2 respectively. Calculate Digit Verification of CAS Registry Number 1910-12: (6*1)+(5*9)+(4*1)+(3*0)+(2*1)+(1*2)=59 59 % 10 = 9 So 1910-12-9 is a valid CAS Registry Number.