The Wednesday Morning Math Challenge: Week 3

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?