The CAS Registry Mumber 37357-68-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,7,3,5 and 7 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 37357-68: (7*3)+(6*7)+(5*3)+(4*5)+(3*7)+(2*6)+(1*8)=139 139 % 10 = 9 So 37357-68-9 is a valid CAS Registry Number.