Here is "this week's" NPR puzzle challenge. Let's see how you do.

Challenge for February 18: The object of this challenge is to develop nine (but see suggested extension below) different mathematical expressions that equal eight. You must use the digits 2, 7 and one other. And that other digit must be a one in the first expression, two in the next expression and so on, up to nine. You can use a digit once and only once in each expression.

(Suggested extension to the problem : besides 1 thru 9, include 0, 10, 11 and 13)

You may use the four arithmetic symbols (plus, minus, times and divided by), as well as exponents and decimal points. You may use parentheses as you need them. For example: Using the digits 2, 7 and 1, you can make the expression 2+7-1=8.

This week's Challenge is from Robert Wainwright in New Rochelle, N.Y.

(My comments to Howard follow.)

I've figured out 1 thru 6, 8 and 9. I've spent a total of about maybe an hour in two sessions while on runs and so far, still can't figure out 7. One thing that's interesting is, once I get them, I have some trouble remembering them and so it's good I've finally written them down so I can recall them. If you don't care to see my solutions because you are still working on this, don't click the link at the bottom of this page!

Late Breaking! Thanks to Roger Bessette, 7 is now known. And, along the way, John Stokes found another solution for 1.

Late Late Breaking! Another solution for 3 and another solution for 9 have been found. A proposed solution for 9 and a proposed solution for 12 have been ruled illegal and have been removed.