Why is it always 1089
(This is the reasoning behind Always End With 1089)
WE will need a little bit of algebra.
But stick with it, it is not difficult.
Represent the number with ABC
Reverse this to get CBA
Remember that A is Hundreds B
is tens and C is units
Take CBA from ABC like this
Now here is the trick:
Subtract 1 Hundred, and add 9 Tens and 10 Ones
(-100, +90, +10 = 0, so won't change answer):
Last Step: Reverse the answer and
add the two numbers together.
As predicted the answer was 1089