The CAS Registry Mumber 1257642-72-0 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,2,5,7,6,4 and 2 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 1257642-72: (9*1)+(8*2)+(7*5)+(6*7)+(5*6)+(4*4)+(3*2)+(2*7)+(1*2)=170 170 % 10 = 0 So 1257642-72-0 is a valid CAS Registry Number.