The CAS Registry Mumber 83790-93-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,3,7,9 and 0 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 83790-93: (7*8)+(6*3)+(5*7)+(4*9)+(3*0)+(2*9)+(1*3)=166 166 % 10 = 6 So 83790-93-6 is a valid CAS Registry Number.