Welcome to Week 3 of the Wednesday Morning Math Challenge. You can find solutions to the Week 2 puzzles here, along with — more importantly — discussions of some ways to approach them. Remember that the real goal here is to think creatively.

Here are three new problems. This week we’re playing around with digits.

**1.** You are given the numbers 2, 4, 6, and 8. Can you think of an expression using only elementary operations (+,-,x,/) and each of those numbers once that results in 25?

**2.** You already know what a perfect square is from week 1. How many perfect squares are numbers whose digits are all the same? (For example, 222 or 3333.)

**3.** What four digit (whole) number is the square root of a number with the same last four digits?