In #14 the difference between the last four numbers when grouped as two figures is always the second digit in each number, ie:
571219: 19-12=7
841216: 16-12=4
791615: ODD ONE OUT
471118: 18-11=7
781523: 23-15=8
Hey there, I just did this test and on the version I have question #13 is different, in that the first number in the second row is 18, not 19. The answer then becomes 5. Thought it was worth mentioning given every other question is exactly the same.