Question 694287: There is a 3digit number in which the 2nd digit is the sum of the 1st and 3rd digit. Can you prove that the number is divisible by 11? Answer by KMST(5328) (Show Source):
You can put this solution on YOUR website! Yes.
As a matter of fact, that is the way to multiply a two digit number times 11.
It is very easy, as long as the sum of those digits is less than 10.
You just write the two digits, leaving some space in the middle, and then write the sum in that middle space. = first (hundreds) digit = third (ones) digit
Then, second (tens) digit = ,
and the value of the 3-digit number is is the 2-digit number with as a first (tens) digit and as a second (ones) digit.
The 3-digit number in the problem is times the two digit number ab.
