6999

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Number

$6999$ (six thousand, nine hundred and ninety-nine) is:

$3 \times 2333$

The $1$st of the $4$-digit integers $m$ which need the largest number of reverse-and-add process iterations ($20$) before reaching a palindromic number:

$6999$, $16995$, $76956$, $\ldots$, $16668488486661$

Also see

• Next: 4-Digit Numbers forming Longest Reverse-and-Add Sequence

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $6999$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $6999$