Holes in Numbers

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Have you ever noticed that $0$ , $6$ , $8$ and $9$ have holes in them?

An interesting problem is to count such holes in a given number.

For example, the number $68724$ and $59013$ have $3$ and $2$ holes respectively.

Counting the holes in relatively small numbers are pretty easy, but how about finding the holes in a 500 digits number?

How many holes are there in the 500-digits number?

You can find the number here .

The answer is 304.

2 solutions

Lokesh Sharma
Feb 4, 2014

Finding holes in a 500 digits number is also pretty easy #_#

Python Solution:

s = '73475170547837298717289758738741902738962561728347902759816985230714827956107148923074836125897109823749812689356198072384798216398719856289178293749628510738497382965819072384718926589107389478912635812703894712935689127985723980719872398727340926358961098738472983065817083748972389751628356207348972037581969587832974089275868932724780217259837982783061985693274892507937857091738658327894702891789568397490723817085689730782789175873895793879480718739075893784278461856536821849023583798638291075'
tot = 0
for i in s:
    if i == '8':
        tot += 2
    elif i == '6' or i == '0' or i == '9':
        tot += 1

print tot        

>>> 304

Alds Ramos
Jan 24, 2014

Solution Using Java

public class holes {
        public static void main(String[] args)
    {
        String numb =   "73475170547837298717289758738741902738962561728347902759816985230714827956107148923074836125897109823749812689356198072384798216398719856289178293749628510738497382965819072384718926589107389478912635812703894712935689127985723980719872398727340926358961098738472983065817083748972389751628356207348972037581969587832974089275868932724780217259837982783061985693274892507937857091738658327894702891789568397490723817085689730782789175873895793879480718739075893784278461856536821849023583798638291075";
        int hole = 0;
        for(int i=0; i<numb.length(); i++)
        {
            switch(numb.charAt(i))
            {
                case '0': hole++; break;
                case '6': hole++; break;
                case '8': hole+=2; break;
                case '9': hole++; break;
            }
        }
        System.out.println(hole);
    }
}

Holes in Numbers

The answer is 304.

2 solutions

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