mathcounts notes

1. Example: How many diagonals can be drawn for a polygon with “n” sides? Method I: The number of diagonals in a polygon = n(n-3)/2, wher...

Word problems on unit digit, tenth digit or digit sum. #1: How many digits are there in the positive integers 1 to 99 inclusive?  Sol...

Questions: #1: At a county fair, if adults to kids ratio is 2 to 3 and there are 250 people at the fair. How many adults and how many kids?...

Mental Math Practices: All questions can be solved in your head reasonably fast (less than 5 minutes) if you understand the concepts well. ...

The following sequences are all arithmetic sequences and for any arithmetic sequences, the sum is  always average times the terms (how ma...

Please refrain yourself from checking the answers too soon. Use Lego blocks, unit cubes, or Rubik's cubes to help you think. If you are...

   Learn basic facts here. Another fun trick is to find the total number of factors any number has. To do this, take the...

Please give me feedback on the comment. Thanks a lot!!  Mrs. Lin These are the two most common right triangles. For 45-45...

Please write a comment and give me feedback. Thanks a lot!! Quite a lot of my students have problems figuring out this type of problems so...

Q: How many ways can you make 25 cents if you can use quarters, dimes, nickels or pennies? Start with the largest value: 1 Quarter      1...

This year's Mathcounts' handbook can be downloaded free here . Please take a look at what that program is all about. It's tea...