The CAS Registry Mumber 73895-31-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,3,8,9 and 5 respectively; the second part has 2 digits, 3 and 1 respectively. Calculate Digit Verification of CAS Registry Number 73895-31: (7*7)+(6*3)+(5*8)+(4*9)+(3*5)+(2*3)+(1*1)=165 165 % 10 = 5 So 73895-31-5 is a valid CAS Registry Number.