The CAS Registry Mumber 769881-83-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 7,6,9,8,8 and 1 respectively; the second part has 2 digits, 8 and 3 respectively. Calculate Digit Verification of CAS Registry Number 769881-83: (8*7)+(7*6)+(6*9)+(5*8)+(4*8)+(3*1)+(2*8)+(1*3)=246 246 % 10 = 6 So 769881-83-6 is a valid CAS Registry Number.