The CAS Registry Mumber 123762-56-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,3,7,6 and 2 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 123762-56: (8*1)+(7*2)+(6*3)+(5*7)+(4*6)+(3*2)+(2*5)+(1*6)=121 121 % 10 = 1 So 123762-56-1 is a valid CAS Registry Number.