Check what the result would have been if Sundaram had chosen the numbers shown below.
Let choosen number be abc then,
abc = 100a + 10b + c
cab = 100c + 10a + b
bca = 100b + 10c + a
After adding all the above three, abc + cab + bca = 111(a + b + c) = 37 × 3(a + b + c),
It will be divisible by 37 becuase 37 is present in the equation.
here a = 4, b = 1, and c = 7
417 + 741 + 147 = 1332 = 37*36 i.e. divisible by 37.