## Project Euler Problem 13 Solution

Large sum

by {BetaProjects} | Project Euler & HackerRank

### Project Euler Problem 13 Statement

Work out the first ten digits of the sum of the following one-hundred 50-digit numbers.

```37107287533902102798797998220837590246510135740250
46376937677490009712648124896970078050417018260538
… {data continues}```

### Solution

Summing a set of 50–digit numbers uses Python’s intrinsic arbitrary–precision integers and arithmetic.

The numbers to add are saved to a file named pe13.txt. This keeps the data and the program separate and the process easy to comprehend.

The file is read as strings and converted to a list of integers using the `map` function with `open` as the iterator and `int` as the application function. After the end of the file is reached the list is fed to the `sum` function which adds the integers together.

`total = sum(map(int, open('pe13.txt')))`

Finally, the integer sum, `total`, is converted to a string and truncated to the top 10 digits for a solution.

`str(total)[:10]`

#### HackerRank version

HackerRank increases the quantity of 50–digit numbers from 100 to 1,000. No changes are required.

### Python Source Code

``````total = sum(map(int, open('pe13.txt')))
print ("Top 10 digits of sum =", str(total)[:10])	``````

### Last Word

The data file, pe13.txt, is available on repl.it page by clicking the files  icon in the top left corner.