Thursday, 8 May 2014

Magic 9's

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 ; )

1 comment:

  1. I'm not a mathmagician, but I love nerdy arithmetic stuff! Thanks!