The CAS Registry Mumber 61607-22-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,1,6,0 and 7 respectively; the second part has 2 digits, 2 and 2 respectively. Calculate Digit Verification of CAS Registry Number 61607-22: (7*6)+(6*1)+(5*6)+(4*0)+(3*7)+(2*2)+(1*2)=105 105 % 10 = 5 So 61607-22-5 is a valid CAS Registry Number.