If there is a four digit number $\overline{abcd}$ (not multiplied, just digits) and $1.5\times \overline{abcd}$ is equal to $\overline{dcba}$, how would you solve it?
I have no idea where to start... can someone help me out?
2026-03-30 01:28:35.1774834115
A four digit number reversed
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You have to analyze possible cases.
First of all, $d$ times $3/2$ must be an integer, and it can't be $0$ if we don't allow a leading zero in $abcd$.
This leaves $d \in \{2,4,6,8\}$.
As a leading $d$ this reduces the possibilities for $a$, etc. etc.
What also might help is observing that $3 \times abcd - 2 \times dcba = 0$