Since, 237 > 81
On applying Euclid’s division algorithm, we get
237 = 81 × 2 + 75 ...(i)
81 = 75 × 1 + 6 ...(ii)
75 = 6 × 12 + 3 ...(iii)
6 = 3 × 2 + 0 ...(iv)
Hence, and HCF (81, 237) = 3.
In order to write 3 in the form of 81x + 237y,
we move backwards as follows :

Hence, x = – 38 and y = 13
Note : The values of x and y are not unique.