On Tuesday, July 10, ToddAndMargo wrote: > $ echo "5" | p6 'my $N=slurp(); say $N*($N+1)/2;' > 15 > > $ echo "6" | p6 'my $N=slurp(); say $N*($N+1)/2;' > 21 > > $ echo "100" | p6 'my $N=slurp(); say $N*($N+1)/2;' > 5050
Another cool thing is that this formula is used in Perl 6 under the hood to calculate the sum of the integers in a range instantly: ~ $ time perl6 -e 'say [+] 1..100' 5050 real 0m0.213s user 0m0.250s sys 0m0.032s ~ $ time perl6 -e 'say [+] 1..10000000000000000000' 50000000000000000005000000000000000000 real 0m0.198s user 0m0.236s sys 0m0.034s
