The CAS Registry Mumber 74710-70-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,7,1 and 0 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 74710-70: (7*7)+(6*4)+(5*7)+(4*1)+(3*0)+(2*7)+(1*0)=126 126 % 10 = 6 So 74710-70-6 is a valid CAS Registry Number.