perplexus.info :: Probability : Same digits II

Same digits II (Posted on 2022-06-17)

Choose two distinct non-zero digits. Evaluate the sum of the product and the s.o.d. of the pair.

What is the probability that the result is the concatenation of the initially selected digits?

Example: if the digits were 4,7 the resulting 4*7+7+4=39, not the case you were after, i.e. 47 or 74

See The Solution Submitted by Ady TZIDON

Rating: 4.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)

re(2): Solution

Comment 3 of 3 |

(In reply to re: Solution by Jer)

Right. An algebraic proof is pretty straightforward.

But it still is not intuitively obvious to me; I did a little program to get the result and it surprised me.

Posted by Larry on 2022-06-17 13:02:14

Please log in:

Forums (1)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (6)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:


perplexus dot info