The CAS Registry Mumber 94956-56-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,4,9,5 and 6 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 94956-56: (7*9)+(6*4)+(5*9)+(4*5)+(3*6)+(2*5)+(1*6)=186 186 % 10 = 6 So 94956-56-6 is a valid CAS Registry Number.