Bit of random blogging here, but thought I'd share anyway. I can't remember when i discovered this, but whenever i mention it to anyone they haven't heard about it. I think it's even sometimes taught in schools as a way of helping with nine times tables (you can always double check your answer). You can find examples of why it works, mathematically, online. I just like knowing it. Here it is *drum roll*...... no matter what you multiply nine by if you add up the resulting digits it will always end up coming out as nine. Try it, grab that calculator.
9 x 9=81 8+1= 9
9 x 25= 225 2+2+5=9
9 x 3587= 32,283 3+2+2+8+3= 18 1+8=9
9 x 568798765= 5,119,188,885 added together= 54 5+4=9
and you can go on all day, it will always come back to 9.
Now go bore someone ; )