The CAS Registry Mumber 105253-67-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,5,2,5 and 3 respectively; the second part has 2 digits, 6 and 7 respectively. Calculate Digit Verification of CAS Registry Number 105253-67: (8*1)+(7*0)+(6*5)+(5*2)+(4*5)+(3*3)+(2*6)+(1*7)=96 96 % 10 = 6 So 105253-67-6 is a valid CAS Registry Number.