The CAS Registry Mumber 87783-60-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,7,7,8 and 3 respectively; the second part has 2 digits, 6 and 0 respectively. Calculate Digit Verification of CAS Registry Number 87783-60: (7*8)+(6*7)+(5*7)+(4*8)+(3*3)+(2*6)+(1*0)=186 186 % 10 = 6 So 87783-60-6 is a valid CAS Registry Number.