Excel BI - Excel Challenge 758

excel-challenges

excel-formulas

🔰 Step 1 - Sum the square of the digits.

Published

March 24, 2026

Illustration for Excel BI - Excel Challenge 758

Challenge Description

🔰 Step 1 - Sum the square of the digits. Step 2 - Sum the square of the digits of the result of Step 1. You need to keep doing it till the sum becomes a single digit. List first 5 consecutive

Solutions

library(tidyverse)
library(readxl)
library(memoise)

path = "Excel/700-799/758/758 First 5 Consecutive Happy Numbers.xlsx"
test = read_excel(path, range = "A1:A6") %>% pull()

is_happy = memoise(function(n) {
  repeat {
    n = sum((as.integer(strsplit(as.character(n), "")[[1]]))^2)
    if (n == 1) return(TRUE)
    if (n == 4) return(FALSE)
  }
})

find_consec_happy_seq = function(k) {
  n = 1
  repeat {
    if (all(sapply(n:(n+k-1), is_happy))) return(n:(n+k-1))
    n = n + 1
  }
}

result = find_consec_happy_seq(5)
all.equal(result, test)
# > [1] TRUE

Logic: Read the workbook ranges needed for the challenge.
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
from functools import lru_cache

path = "700-799/758/758 First 5 Consecutive Happy Numbers.xlsx"
test = pd.read_excel(path, usecols="A", nrows=6).iloc[:, 0].tolist()

@lru_cache(maxsize=None)
def is_happy(n):
    while True:
        n = sum(int(digit) ** 2 for digit in str(n))
        if n == 1:
            return True
        if n == 4:
            return False

def find_consec_happy_seq(k):
    n = 1
    while True:
        if all(is_happy(x) for x in range(n, n + k)):
            return list(range(n, n + k))
        n += 1

result = find_consec_happy_seq(5)
print(result == test) # 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.