For example, ISBN 10 uses its 10th digit as the check digit. It's the value that when added to all other digits multiplied by some weight must be divisible by 11.
$(10x_{1}+9x_{2}+8x_{3}+7x_{4}+6x_{5}+5x_{6}+4x_{7}+3x_{8}+2x_{9}+x_{{10}})\mod {11}\equiv 0.$
If we increased 11 to a bigger number, such as 67, and also changed the weights to random values between 2 and 66 would it be more secure?
With this I mean that by putting random numbers we would have a smaller chance of hitting a correct ISBN, since the modulo is bigger the sum would "warp" back to 0 less times in the same interval.