Excel BI - Excel Challenge 882

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excel-formulas

🔰 Numbers Answer Expected Step 1 : Take the number Step 2 : Reverse the number Step 3 : Add Step 1 + Step 2 Repeat steps 1 through 3 till the number becomes Palindrome.

Published

March 24, 2026

Illustration for Excel BI - Excel Challenge 882

Challenge Description

🔰 Numbers Answer Expected Step 1 : Take the number Step 2 : Reverse the number Step 3 : Add Step 1 + Step 2 Repeat steps 1 through 3 till the number becomes Palindrome. Determine the final Palindrome number. Ex. 56 => 56+65 = 143 => 143+341 => 484 which is a Palindrome number

Solutions

library(tidyverse)
library(readxl)

path <- "Excel/800-899/882/882 Reverse Add Palindrome.xlsx"
input <- read_excel(path, range = "A1:A51")
test <- read_excel(path, range = "B1:B51")

is_palindrome <- function(x) {
  s <- as.character(x)
  s == paste(rev(strsplit(s, "")[[1]]), collapse = "")
}

solve_pals <- function(n) {
  purrr::accumulate(
    .x = 0:1000,
    .init = n,
    .f = function(current, .) {
      rev_num <- as.numeric(paste0(
        rev(strsplit(as.character(current), "")[[1]]),
        collapse = ""
      ))
      current + rev_num
    }
  ) -> seqs
  idx <- purrr::detect_index(seqs, is_palindrome) - 1
  return(palindrome = seqs[[idx + 1]])
}

result = input %>%
  mutate(`Answer Expected` = map_dbl(Numbers, solve_pals))

all.equal(result$`Answer Expected`, test$`Answer Expected`)
# [1] TRUE

Logic: Read the workbook ranges needed for the challenge; Derive the required intermediate columns.
Strengths: The code maps the workbook rule into a compact, reproducible pipeline.
Areas for Improvement: The solution assumes the workbook layout and selected ranges remain stable, so any structural change in the sheet would require small adjustments.
Gem: The elegant part is how little code is needed once the correct intermediate representation is chosen.

import pandas as pd

path = "Excel/800-899/882/882 Reverse Add Palindrome.xlsx"
input = pd.read_excel(path, usecols="A", nrows=51)
test = pd.read_excel(path, usecols="B", nrows=51)

def is_palindrome(x):
    s = str(x)
    return s == s[::-1]

def solve_pals(n):
    current = n
    for _ in range(1001):
        if is_palindrome(current):
            return current
        rev_num = int(str(current)[::-1])
        current += rev_num
    return current  

input['Answer Expected'] = input['Numbers'].apply(solve_pals)
print(input['Answer Expected'].equals(test['Answer Expected'])) # True

The Python version keeps the algorithm explicit, which helps when the challenge depends on a greedy or iterative rule.

Difficulty Level

Easy / Medium

The business rule is clear, though the workbook still needs a few transformation steps to reach the expected output.