The CAS Registry Mumber 69903-87-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,9,9,0 and 3 respectively; the second part has 2 digits, 8 and 7 respectively. Calculate Digit Verification of CAS Registry Number 69903-87: (7*6)+(6*9)+(5*9)+(4*0)+(3*3)+(2*8)+(1*7)=173 173 % 10 = 3 So 69903-87-3 is a valid CAS Registry Number.