Prime numbers 2 is the smallest prime number 2 is the only prime even number 1 is not a prime 3, 5, 7 are the only three consecutive odd integers that are each a prime. Digits In the integer 5,432, 5 is the thousands digit, 4 is the hundreds digit, 3 is the tens […]

# Archive | Factorials

## Revised GRE Math Question Re-spin — The Best Way to Get Ready for the New GRE!

By Chris Lele on May 10, 2011 , UPDATED ON June 20, 2013, in Combinations and Permutations, Factorials, Math Concepts, New GRE vs. Old GRE

Try this question out and see how you do. Which of the following is NOT a factor of ? 17 21 25 29 42 51 85 121 Factorials can be intimidating. First off, it’s very difficult to calculate factorials over 6, much less find the factors. However, when finding the factors of a factorial, we […]

## It’s Not An Excited Number; It’s a Factorial!

By Chris Lele on February 17, 2011 , UPDATED ON March 14, 2012, in Factorials, Integer Properties, Math Concepts

If you’ve ever come across a number with an exclamation mark in front of it, that’s the factorial sign, e.g. 5!. Factorials don’t come up too often on the GRE, and when they do, it’s usually on harder problems. Still, you don’t want to be faced with an exclamation sign next to a number and […]