The CAS Registry Mumber 1257650-61-5 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,2,5,7,6,5 and 0 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 1257650-61: (9*1)+(8*2)+(7*5)+(6*7)+(5*6)+(4*5)+(3*0)+(2*6)+(1*1)=165 165 % 10 = 5 So 1257650-61-5 is a valid CAS Registry Number.