The CAS Registry Mumber 107651-34-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,7,6,5 and 1 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 107651-34: (8*1)+(7*0)+(6*7)+(5*6)+(4*5)+(3*1)+(2*3)+(1*4)=113 113 % 10 = 3 So 107651-34-3 is a valid CAS Registry Number.