The CAS Registry Mumber 37442-81-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,7,4,4 and 2 respectively; the second part has 2 digits, 8 and 1 respectively. Calculate Digit Verification of CAS Registry Number 37442-81: (7*3)+(6*7)+(5*4)+(4*4)+(3*2)+(2*8)+(1*1)=122 122 % 10 = 2 So 37442-81-2 is a valid CAS Registry Number.