The CAS Registry Mumber 76853-90-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,8,5 and 3 respectively; the second part has 2 digits, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 76853-90: (7*7)+(6*6)+(5*8)+(4*5)+(3*3)+(2*9)+(1*0)=172 172 % 10 = 2 So 76853-90-2 is a valid CAS Registry Number.