We saw a piece of graffiti that must have been painted by someone with a mathematical and sadistic side to them. It read as follows:
19387
7839
938
83
?
Obviously this is challenging the people who see it to work out what number replaces the question mark.
So what is it? Can you work it out?
There is no mathematical relationship between the successive numbers, so it must be something else. And that something else is "remove the first digit and reverse the digits remaining". Which means that the next, and as it turns out final, number is 3.