Warning! SPOILER!i need to know the spoiler.
If you wanna know the math....
Take 2 digits (say 2 & 9)...you pick 29
Which can also be written as 2*10 + 9
so the first part is
(2 * 10 + 9) - (2 + 9)
2 * 10 + 9 - 2 - 9 rewritten, distribute the - sign
2 * 10 - 2 + 9 - 9 same, reordered
2 * 10 - 2 9-9 = 0
20 - 2 2*10 = 20
2(10 - 1) pull a 2 out of the equation
2(9)
18
if you substitute x & y for the 2 & 9, you get
(10x + y) - (x + y)
10x + y -x -y
10x - x
x(10-1)
x(9)
You can see all the math really resolves to:
pick a two digit number
multiply the first number by 9
X has to be in the set {1..9}, which gives the results in the set
{9,18,27,36,45,54,63,72,81} (multiples of 9)
If you look at the map of symbols to numbers, the answer set all have the same symbol...the symbols rotate from run to run to make it less obvious...
edits: typos
If you wanna know the math....
Take 2 digits (say 2 & 9)...you pick 29
Which can also be written as 2*10 + 9
so the first part is
(2 * 10 + 9) - (2 + 9)
2 * 10 + 9 - 2 - 9 rewritten, distribute the - sign
2 * 10 - 2 + 9 - 9 same, reordered
2 * 10 - 2 9-9 = 0
20 - 2 2*10 = 20
2(10 - 1) pull a 2 out of the equation
2(9)
18
if you substitute x & y for the 2 & 9, you get
(10x + y) - (x + y)
10x + y -x -y
10x - x
x(10-1)
x(9)
You can see all the math really resolves to:
pick a two digit number
multiply the first number by 9
X has to be in the set {1..9}, which gives the results in the set
{9,18,27,36,45,54,63,72,81} (multiples of 9)
If you look at the map of symbols to numbers, the answer set all have the same symbol...the symbols rotate from run to run to make it less obvious...
edits: typos