(In reply to

re(3): Solution by Charlie)

__C l a r i f i c a t I o n__

A number N is called frugal if the number of digits in its prime factorization (including exponents greater than 1) is smaller than the number of digits of N.

A number N is called equidital if the number of digits in its prime factorization (including exponents greater than 1) is equal to the number of digits of N.

For example, 2048=2^11 is frugal.

The union of frugal and equidigital numbers gives economical numbers.

**Some authors call the frugal numbers economical.**

Every number greater than 1923 can be written as a sum of frugal numbers.

*Edited on ***March 18, 2017, 11:12 am**