scale=90
for (e = n = f = 1; f != 0; f /= ++n) e += f
e

Palindromic primes

20 FOR N=2 TO 100000
30 I=N
35 J=0
40 J=J*10+I-INT(I/10)*10
43 I=INT(I/10)
47 IF I>0 THEN 40
50 IF J<>N THEN 80
52 IF N=2 THEN 75
60 FOR I=2 TO SQR(N)
65 IF N-INT(N/I)*I=0 THEN 80
70 NEXT I
75 PRINT N;" ";
80 NEXT N
85 PRINT

Palindate

#! /bin/bash
is_palyndrom_date() { date -d "$1" 1>/dev/null 2>&1 && echo "$1" ; }
for _H in {2..9}; do
 for _I in {0..9}; do
  for _J in {0..99}; do
   is_palyndrom_date ${_H}${_I}`printf "%02d%s" ${_J}`-`printf "%02d%s" ${_J} |
rev`-`printf "%02d%s" ${_H}${_I} | rev`
  done
 done
done

Shuffle and deal four hands of five cards each with #Python

#!/usr/bin/python3
import random
deck = [
'🂡','🂢','🂣','🂤','🂥','🂦','🂧','🂨','🂩','🂪','🂫','🂭','🂮',
'🂱','🂲','🂳','🂴','🂵','🂶','🂷','🂸','🂹','🂺','🂻','🂽','🂾',
'🃁','🃂','🃃','🃄','🃅','🃆','🃇','🃈','🃉','🃊','🃋','🃍','🃎',
'🃑','🃒','🃓','🃔','🃕','🃖','🃗','🃘','🃙','🃚','🃛','🃝','🃞'
]
random.shuffle(deck)
for i in range(0, 20, 5):
    print(" ".join(deck[i:i+5]))

Highlight consecutive duplicated words with Perl

perl -pe 's/\b(\w+)\s+\1\b/\e[31m$&\e[0m/gi' gettysburg.txt

#! /usr/bin/bc -l
define t(x) {
        return s(x) / c(x)
}
define y(y) {
        if (y == -1) return -2 * a(1)  /* -pi/2 */
        if (y == 1) return 2 * a(1)    /* pi/2 */
        return a(y / sqrt(1 - y * y))
}
define x(x) {
        auto a
         if (x == 0) return 2 * a(1)  /* pi/2 */
        a = a(sqrt(1 - x * x) / x)
        if (a < 0) {
                return a + 4 * a(1)  /* add pi */
        } else {
                return a
        }
}
p = 4 * a(1)  /* pi */
d = p / 180   /* one degree in radians */
"Using radians:
"
"sin(-pi / 6) = "; s(-p / 6)
"cos(3 * pi / 4) = "; c(3 * p / 4)
"tan(pi / 3) = "; t(p / 3)
"asin(-1 / 2) = "; y(-1 / 2)
"acos(-sqrt(2) / 2) = "; x(-sqrt(2) / 2)
"atan(sqrt(3)) = "; a(sqrt(3))

"Using degrees:
"
"sin(-30) = "; s(-30 * d)
"cos(135) = "; c(135 * d)
"tan(60) = "; t(60 * d)
"asin(-1 / 2) = "; y(-1 / 2) / d
"acos(-sqrt(2) / 2) = "; x(-sqrt(2) / 2) / d
"atan(sqrt(3)) = "; a(sqrt(3)) / d
quit

With Python find words longer than 10 characters that use all the vowels:

#! /usr/bin/env python3
with open('unixdict.txt') as f:
    while (line := f.readline().strip()):
        if (len(line) > 10 and all(
                line.count(c) == 1 for c in 'aeiou')):
            print(line)

Number to words

#!/usr/bin/env python3
import sys
n = int(sys.argv[1])
ones = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"]
teens = ["ten", "eleven", "twelve", "thirteen", "fourteen","fifteen", "sixteen", "seventeen", "eighteen", "nineteen"]
tens = ["", "", "twenty", "thirty", "forty","fifty", "sixty", "seventy", "eighty", "ninety"]
if n < 10:
    print(ones[n])
elif n < 20:
    print(teens[n - 10])
else:
    t = n // 10
    o = n % 10
    if o == 0:
        print(tens[t])
    else:
        print(f"{tens[t]}-{ones[o]}")

Archimedes spiral with turtle graphics

#!/usr/bin/env python3
from turtle import *
from math import *
color("blue")
speed(0)
down()
for i in range(200):
    t = i*pi/20
    r = 1+5*t
    goto(r*cos(t), r*sin(t))
done()