The CAS Registry Mumber 7248-75-1 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,2,4 and 8 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 7248-75: (6*7)+(5*2)+(4*4)+(3*8)+(2*7)+(1*5)=111 111 % 10 = 1 So 7248-75-1 is a valid CAS Registry Number.