The CAS Registry Mumber 1359865-98-7 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,3,5,9,8,6 and 5 respectively; the second part has 2 digits, 9 and 8 respectively. Calculate Digit Verification of CAS Registry Number 1359865-98: (9*1)+(8*3)+(7*5)+(6*9)+(5*8)+(4*6)+(3*5)+(2*9)+(1*8)=227 227 % 10 = 7 So 1359865-98-7 is a valid CAS Registry Number.