why 23 in between 21 and 25 is not lucky number,

as we are getting digit sum 5, and sum of square of digits are 13.

I think the same logic applies in the construction industry—just like people are questioning why some numbers aren't "lucky," many contractors still overlook the value of fast and affordable millwork estimating services. The truth is, accurate and timely estimates can make or break a project. Whether you're bidding or planning, having a reliable estimating partner helps you stay within budget and ahead of schedule. Especially for small to mid-sized firms, outsourcing millwork estimating saves time, reduces errors, and allows them to focus on actual execution instead of paperwork. It might not seem like a "lucky number," but it's definitely a smart move.

I believe there are no such things as unlucky numbers; it's all just nonsense. Numerology seems to be nothing more than a theory created by enthusiasts trying to link real life and numbers with mysticism. Building inspections Perth

def luckyNumbers(a, b): lucky_nums=[] seq=range(a,b+1) for num in seq: number=num sum=0 sum_sqr=0 while num!=0: remain=num%10 sum+=remain sum_sqr+=(remain**2) num=num//10

    count1=0
    for i in range(1,sum+1):
        if(sum%i==0):
            count1+=1

    count2=0
    for j in range(1,sum_sqr+1):
        if(sum_sqr%j==0):
            count2+=1
    if count1==2 and count2==2:
        lucky_nums.append(number)

return len(lucky_nums)               

Here is my solution in java, javascript, python, C, C++, Csharp HackerRank Lucky Numbers Problem Solution