The CAS Registry Mumber 36341-72-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,6,3,4 and 1 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 36341-72: (7*3)+(6*6)+(5*3)+(4*4)+(3*1)+(2*7)+(1*2)=107 107 % 10 = 7 So 36341-72-7 is a valid CAS Registry Number.