## Teaser 2812: Sum card trick

**From The Sunday Times, 14th August 2016** [link]

Joe has nine cards, white on one side and grey on the other, with a single digit written on each side of each card. He gave them to Penny to arrange white-side-up to form three 3-figure numbers with the sum of the first two equalling the third. This was her attempt:

(2 1 9) (6 5 4) (8 7 3)Then Joe turned the cards over one at a time to reveal

(9 8 7) (1 4 2) (3 6 5)where the total of the first two did not equal the third. So he challenged Penny to arrange the cards so that both white-side-up and grey-side-up the third number was the sum of the first two, which she did.

What was her third grey number?

[teaser2812]

## Jim Randell 8:17 am

on8 July 2019 Permalink |The following run file uses the [[

`--code`

]] parameter of the [[`SubstitutedExpression()`

]] solver (from theenigma.pylibrary) to provide a function that translates from white numbers to grey numbers. This can then be used in the alphametic expressions.The run file executes in 236ms.

Run:[ @repl.it ]Solution:The third grey number is 738.LikeLike

## GeoffR 8:41 am

on16 July 2019 Permalink |LikeLike