The CAS Registry Mumber 157087-65-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,7,0,8 and 7 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 157087-65: (8*1)+(7*5)+(6*7)+(5*0)+(4*8)+(3*7)+(2*6)+(1*5)=155 155 % 10 = 5 So 157087-65-5 is a valid CAS Registry Number.