The CAS Registry Mumber 102785-61-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,2,7,8 and 5 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 102785-61: (8*1)+(7*0)+(6*2)+(5*7)+(4*8)+(3*5)+(2*6)+(1*1)=115 115 % 10 = 5 So 102785-61-5 is a valid CAS Registry Number.