The CAS Registry Mumber 102520-45-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,2,5,2 and 0 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 102520-45: (8*1)+(7*0)+(6*2)+(5*5)+(4*2)+(3*0)+(2*4)+(1*5)=66 66 % 10 = 6 So 102520-45-6 is a valid CAS Registry Number.