This Week's Work : Week 50 - for Inquisitive Young Mathletes

Counting Restrictions from Glyia

Very nice introductory level counting questions with restrictions.

from Mathcounts Mini : Counting the Number of Subsets of a Set

 from AoPS :

Counting with Restrictions Part 3  : This one is tricky. Make sure you understand the concepts well.

Try this question from 2011 AMC-8 # 23 :

How many 4-digit positive integers have four different digits, where the leading digit is not zero, the integer is a multiple of 5, and 5 is the largest digit?

Solutions from AoPS

Counting with Combinations Part 3

At our group lessons, we'll continue working on harder Mathcounts concepts, not just the accuracy, but speed.

Take care and happy problem solving !!