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 7 added 339 characters in body edited Jan 23 at 19:04 peterSO 1,68888 silver badges1010 bronze badges Go was designed for Google scale. Therefore, Go package testing includes benchmarking tools. For example,$go test -bench=. -benchmem BenchmarkPeterSO-8 500 3805125 ns/op 1007621 B/op 1 allocs/op BenchmarkNightman-8 1 95703259026 ns/op 5866752 B/op 31 allocs/op$  Go was designed for Google scale. Therefore, Go package testing includes benchmarking tools. For example,$go test -bench=. -benchmem BenchmarkPeterSO-8 500 3805125 ns/op 1007621 B/op 1 allocs/op BenchmarkNightman-8 1 95703259026 ns/op 5866752 B/op 31 allocs/op$  6 added 95 characters in body edited Jan 23 at 18:47 peterSO 1,68888 silver badges1010 bronze badges 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.NowsumPrimes() var n uint64 = 2000000) -uint64 1{ sum := uint64(0) if n >= 2 { sum += 2 } for i, p := range oddPrimes(n) { if p == prime { sum += 2*uint64(i) + 1 } } return sum } func main() { start := time.Now() var n uint64 = 2000000 - 1 sum := sumPrimes(n) fmt.Println(sum) fmt.Println(time.Since(start)) }  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)) }  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 sumPrimes(n uint64) uint64 { sum := uint64(0) if n >= 2 { sum += 2 } for i, p := range oddPrimes(n) { if p == prime { sum += 2*uint64(i) + 1 } } return sum } func main() { start := time.Now() var n uint64 = 2000000 - 1 sum := sumPrimes(n) fmt.Println(sum) fmt.Println(time.Since(start)) }  5 added 41 characters in body edited Jan 23 at 17:21 peterSO 1,68888 silver badges1010 bronze badges The algorithm given in the question is much slower than Eratosthenes' well-known algorithm, approximately 25,000 times slower. The algorithm given in the question is much slower than Eratosthenes' well-known algorithm. The algorithm given in the question is much slower than Eratosthenes' well-known algorithm, approximately 25,000 times slower. 4 Response to Martin R edited Jan 23 at 15:32 peterSO 1,68888 silver badges1010 bronze badges 3 edited body edited Jan 23 at 6:51 peterSO 1,68888 silver badges1010 bronze badges 2 added 5 characters in body edited Jan 23 at 6:35 peterSO 1,68888 silver badges1010 bronze badges 1 answered Jan 23 at 6:30 peterSO 1,68888 silver badges1010 bronze badges