Have you ever known some of the letters in a word but not the first few? A dictionary won't help you, but this app will. It's a crossword puzzle helper. When a crossword puzzle has me stumped I look here for help.

Enter the letters you know and spaces for the letters you don't know. For example, if you're looking for a six-letter word ending in "est", enter " est". Click here for a demo

Enter Pattern:   Search

When you click the search button, this app counts the characters in the submitted text. If there are six characters, for example, it examines all six-letter words in its dictionary looking for words that match the text you entered.

A fun thing to do - if you want to see, for example, all 3-letter words, enter 3 spaces; to see all 4-letter words, enter 4 spaces; and so on.
All 3-letter words All 4-letter words

Have you ever seen a Wheel of Fortune board and wondered what words could fit? This helper app lets you enter the letters as they appear on the board and letters that have already been guessed and then searches its dictionary for words that match the pattern but don't use any of the letters already guessed.

For example, if the pattern looks like "_____L_N_" and the letters C, H, and P have already been guessed, enter "_____L_N_" as the pattern and "CHP" for the guessed letters. Click here for a demo

Enter Pattern: 

Enter Guessed Letters: 

Search

When you click the search button, this app counts the characters in the submitted text. If there are six characters, for example, it examines all six-letter words in its dictionary looking for words that match the criteria you entered.

MIT Technology Review used to have a Puzzle Corner column hosted by Allan Gottlieb. Every January the first problem posed was the so-called "Year" problem. Here's the year problem from 2014, when I first took on the challenge of automating the solution:

Y2014. How many integers from 1 to 100 can you form using the digits 2, 0, 1, and 4 exactly once each; the operators +, -, × (multiplication), / (division) and ^ (exponentiation)? We seek solutions containing the minimum number of operators; among solutions having a given number of operators, those using the digits in the order 2, 0, 1, 4 are preferred. Parentheses may be used for grouping; they do not count as operators. A leading minus sign, however, does count as an operator.

It turns out that it doesn't take very long to try every possible combination of operators and numbers and come up with the best solution. Enter a year in the text box below and click "Solve". Click here for a demo

Note: You can also enter a two or three-digit number and get solutions for that number as well.

Enter Year:   Solve

When comparing solutions the app applies two more rules to get the "best" solution:

• Pick the solution with the fewest parentheses.
• Pick the solution with simpler operators - avoid using minus and divide.

I once read a brain-teaser about 4 flies that are placed at the corners of a square. Each one tries to walk to the adjacent fly, but since they are all moving they follow a spiral path towards the center of the square. I wrote a program to simulate those flies. The result was the first incarnation of "Math Art".

In this demo you can change the colors, number of sides, closing factor, line width, and how many cycles to run the simulation.

Click "Draw" to generate a new image or pick one of these demos: 4 Sides #1  4 Sides #2  6 Sides  9 Sides 

Draw

This demo draws a succession of inscribed polygons. The key parameter is the "Closing Factor". The more closely it approaches 1, the more closely spaced the polygons are and the more faithfully the polygon vertices reproduce the spiral path. I've also created Plitt Math Art, a more full-featured site.