The CAS Registry Mumber 76241-31-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,2,4 and 1 respectively; the second part has 2 digits, 3 and 1 respectively. Calculate Digit Verification of CAS Registry Number 76241-31: (7*7)+(6*6)+(5*2)+(4*4)+(3*1)+(2*3)+(1*1)=121 121 % 10 = 1 So 76241-31-1 is a valid CAS Registry Number.