```> I am trying to find all primes less than 2,000,000 and sum them
> together. My code currently takes 1'36" to run. Is there a faster way
> to get my solution?

----------

Yes. For example,

142913828922
3.860761ms

versus your

142913828922
1m35.090248409s

----------

`prime.go`:

package main

import (
"fmt"
"time"
)

const (
prime    = 0x00
notprime = 0xFF
)

func oddPrimes(n uint64) (sieve []uint8) {
sieve = make([]uint8, (n+1)/2)
sieve[0] = notprime
p := uint64(3)
for i := p * p; i <= n; i = p * p {
for j := i; j <= n; j += 2 * p {
sieve[j/2] = notprime
}
for p += 2; sieve[p/2] == notprime; p += 2 {
}
}
return sieve
}

func main() {
start := time.Now()

var n uint64 = 2000000 - 1
sum := uint64(0)
if n >= 2 {
sum += 2
}
for i, p := range oddPrimes(n) {
if p == prime {
sum += 2*uint64(i) + 1
}
}
fmt.Println(sum)

fmt.Println(time.Since(start))
}

----------

Reference: [Sieve of Eratosthenes - Wikipedia][1]

----------

> Comment: You have presented an alternative solution, but haven't
> works and why it is better than the original) so that the author and
> R](https://codereview.stackexchange.com/users/35991/martin-r)

----------

The thought process is simple, obvious, and well-known.

The prime number problem is well-known.

Therefore, [Standing on the shoulders of giants - Wikipdia](https://en.wikipedia.org/wiki/Standing_on_the_shoulders_of_giants).

"If I have seen further it is by standing on the sholders [sic] of Giants." Isaac Newton

For example, [Sieve of Eratosthenes - Wikipedia](https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes).

The algorithm given in the question is much slower than Eratosthenes' well-known algorithm.

In real-world code reviews, code should be correct, maintainable, robust, reasonably efficient, and, most importantly, readable. The code in the question is not reasonably efficient.

[1]: https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes```