Let \(S\) be the number obtained by writing all the numbers from 1 to 100 in order, and removing the spaces in between. Let \(T \) be the number obtained by writing all the numbers from 1 to 100 in reverse order and removing the spaces in between.
What is the remainder when \( T^2 - S^2 \) is divided by \( 1000 \)?
Details and assumptions
The number obtained by writing all the numbers from 1 to 10 in reverse order and removing the spaces in between, is \( 10987654321\).
by
Calvin Lin
