The CAS Registry Mumber 655251-06-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 6,5,5,2,5 and 1 respectively; the second part has 2 digits, 0 and 6 respectively. Calculate Digit Verification of CAS Registry Number 655251-06: (8*6)+(7*5)+(6*5)+(5*2)+(4*5)+(3*1)+(2*0)+(1*6)=152 152 % 10 = 2 So 655251-06-2 is a valid CAS Registry Number.