I'm confused: If that's not the pic of your keypad, why did you attach it?The pic is for a matrix keyboard; it actually says there in the playground "you can safely ignore any unused keypad pins"
ProcedureConnect your Ohm meter leads to pins 1 and 2.Press all the buttons until the meter indicates a closure.Write down the pin numbers next to the column and row for the key you just found. Example: Your meter is connected to pins 1 and 5. When you pressed the number 7 your meter reacted. Write 1 under COL0 and 5 next to ROW2.If the meter didn't react then move the meter lead from pin 2 to pin 3 and repeat steps 2 and 3 above.Now, keep moving the lead to the next pin and repeat steps 2 and 3 for each pin.Once you have reached the end move the first meter lead from pin 1 to pin 2 and repeat steps 2 and 3 while connecting the second meter lead to pins 3 through the highest pin.Once you have completely identified all the pins on the diagram then you can safely ignore any unused keypad pins. You are now ready to wire the keypad to your Arduino.
Did you read the rest of it?:
Assuming you own an Ohm Meter -