Factoring by trial and error. For Jane's in depth factoring lesson, click the link in the end screen. Jane, a retired university math teacher, started this volunteer project in April 2009. Positive feedback from wonderful viewers worldwide keeps her motivated. Jane is a strong advocate of reading music. She made unconventional sight-reading lessons that simplifies reading music. https://sites.google.com/site/pianoandmathtutorials/sight-reading-lessons