The CAS Registry Mumber 107605-64-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,7,6,0 and 5 respectively; the second part has 2 digits, 6 and 4 respectively. Calculate Digit Verification of CAS Registry Number 107605-64: (8*1)+(7*0)+(6*7)+(5*6)+(4*0)+(3*5)+(2*6)+(1*4)=111 111 % 10 = 1 So 107605-64-1 is a valid CAS Registry Number.