THE PUZZLET PAGE


PUZZLET 148

The Index and Length of Factorials

A factorial is an integer which is the product of its index and all the integers less than its index. Thus, factorial four (denoted 4!) is equal to 4 x 3 x 2 x 1 = 24.

Find all factorials whose length (number of digits) equals  their index. That is, those factorials in which n! contains n digits.

To get you started, the first few factorials are shown in the table
.

Table



MAIN MENU
SOLUTION
ARCHIVES

Site design/maintenance: Dave Ellis E-mail me!
Last Updated: January 14th, 2010.