The CAS Registry Mumber 70664-37-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,0,6,6 and 4 respectively; the second part has 2 digits, 3 and 7 respectively. Calculate Digit Verification of CAS Registry Number 70664-37: (7*7)+(6*0)+(5*6)+(4*6)+(3*4)+(2*3)+(1*7)=128 128 % 10 = 8 So 70664-37-8 is a valid CAS Registry Number.