DRDO Multi tasking staff Model paper 7

We know that, for given two numbers,
L.C.M. × H.C.F. = product of numbers
According to the given information,
L.C.M. = 1560, H.C.F. = 13, First number = 520
∴Second number =

1560×13

520

=39
Hence, the second number is 39.