Question 513546
It works because if you choose some number x (other than 1), the number you obtain is


*[tex \LARGE \frac{x^2 - 1}{x - 1} - x = (x + 1) - x = 1]


Here's one: Choose any positive integer greater than 1. Square it and add 1. Take the factorial of that number (x! = x*(x-1)*...*2*1). Take the units digit of the factorial and multiply it by your original number.