Find prime n such that reversed n is also prime: Difference between revisions
Find prime n such that reversed n is also prime (view source)
Revision as of 22:11, 13 June 2021
, 2 years agoAdded XPL0 example.
(Added XPL0 example.) |
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34 such primes found.
</pre>
=={{header|XPL0}}==
<lang XPL0>func IsPrime(N); \Return 'true' if N is a prime number
int N, I;
[if N <= 1 then return false;
for I:= 2 to sqrt(N) do
if rem(N/I) = 0 then return false;
return true;
];
func Reverse(N); \Return the reverse of the digits in N
int N, M;
[M:= 0;
while N do
[N:= N/10;
M:= M*10 + rem(0);
];
return M;
];
int Count, N;
[Count:= 0;
for N:= 1 to 499 do
[if IsPrime(N) & IsPrime(Reverse(N)) then
[IntOut(0, N);
Count:= Count+1;
if rem(Count/10) = 0 then CrLf(0) else ChOut(0, 9\tab\);
]
];
CrLf(0);
IntOut(0, Count);
Text(0, " reversible primes found.");
]</lang>
{{out}}
<pre>
2 3 5 7 11 13 17 31 37 71
73 79 97 101 107 113 131 149 151 157
167 179 181 191 199 311 313 337 347 353
359 373 383 389
34 reversible primes found.
</pre>
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