The CAS Registry Mumber 99948-61-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,9,9,4 and 8 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 99948-61: (7*9)+(6*9)+(5*9)+(4*4)+(3*8)+(2*6)+(1*1)=215 215 % 10 = 5 So 99948-61-5 is a valid CAS Registry Number.