Can anyone figure this out?

[poz]

This is pretty impressive, and I'm sure I could figure out how it works if I spent enough time, but I'm lazy, so I thought I'd see if any of you guys can nail it pronto......

http://www.regiftable.com/regiftingrobinpopup.html

Cheers

Dan

[nigel_d.]

Yep, you will see in the grid that whatever gift comes up there are several duplicate gifts on different numbers, doubtless the formular can only give the same limited numbers - took a while though.

Next;)

[dean_barker]

Assume:

a in {1..9}

b in {0..9}

x = 10a + b

Solve:

x - a - b = y

(10a + b) - a - b = y

Therefore

9a = y

It follows that y is always a multiple of 9.

If you put the same value in all squares represented by a multiple of 9 (i.e. 9, 18, 27 ... 81) and randomize all other values you're guaranteed to always be correct.

... couldn't help myself.

[spigot]

Its Witchcraft I tell ye.

[cobra]

she got it wrong every time because i did not hover the mouse over the answer

[macey2kk]

Assume:

a in {1..9}

b in {0..9}

x = 10a + b

Solve:

x - a - b = y

(10a + b) - a - b = y

Therefore

9a = y

It follows that y is always a multiple of 9.

If you put the same value in all squares represented by a multiple of 9 (i.e. 9, 18, 27 ... 81) and randomize all other values you're guaranteed to always be correct.

... couldn't help myself.

jesus dean.....have you entered the krypton factor this year!! lol