The CAS Registry Mumber 15087-42-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,5,0,8 and 7 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 15087-42: (7*1)+(6*5)+(5*0)+(4*8)+(3*7)+(2*4)+(1*2)=100 100 % 10 = 0 So 15087-42-0 is a valid CAS Registry Number.