why do modulus by 1 code example

Example: what is modulus operator

// given a list of widgets, files, people, etc.
longList = 10000; 
feedbackInterval = 100; // to be used as the modulus

// loop over the list to process each item
for( i=1; i <= longList; i++ ) {
	
  // perform some operation
	
  // mod operation gives feedback once every hundred loops
  if( i % feedbackInterval == 0 ) {
    percentCompleted = ( i / longList ) * 100;
    writeOutput( "#percentCompleted# percent complete. " );
  }
	
}