KMC 2017 Cadet No. 30 Quadrilateral Area within a Parallelogram   Question and Solution are in Images below:                        

*I received a nice message from Mr. Lee Eming (Ex-Brainbuilder & currently TeamMathics’ General Manager) regarding the KMC training materials I developed for their use during my time with them (for Pre-Ecolier, Ecolier & Benjamin categories): Thank you sir for your kind acknowledgement; it was a “team effort”.

  Question: Yesterday I wrote down my friend Ekin’s telephone number. The telephone number on my note has six digits, but I remember that Ekin said that the number had seven digits. I have no idea what digit I forgot to write down, or its position in the number. How many different telephone numbers...