A positive integer is called "maybe prime" if all of its digits are primes and the number is not divisible by 2 or 3. Find the number of positive integers less than 10000 that are "maybe prime".
clc
ct=0;
pDigs='2357';
for n=1:10000
if mod(n,3)~=0 && mod(n,2)~=0
ns=num2str(n);
if length(setdiff(ns,pDigs))==0
disp(n);
ct=ct+1;
end
end
end
ct
finds 170 of them:
5
7
23
25
35
37
53
55
73
77
223
227
233
235
253
257
275
277
323
325
335
337
353
355
373
377
523
527
533
535
553
557
575
577
725
727
733
737
755
757
773
775
2225
2227
2233
2237
2255
2257
2273
2275
2323
2327
2333
2335
2353
2357
2375
2377
2525
2527
2533
2537
2555
2557
2573
2575
2723
2725
2735
2737
2753
2755
2773
2777
3223
3227
3233
3235
3253
3257
3275
3277
3323
3325
3335
3337
3353
3355
3373
3377
3523
3527
3533
3535
3553
3557
3575
3577
3725
3727
3733
3737
3755
3757
3773
3775
5225
5227
5233
5237
5255
5257
5273
5275
5323
5327
5333
5335
5353
5357
5375
5377
5525
5527
5533
5537
5555
5557
5573
5575
5723
5725
5735
5737
5753
5755
5773
5777
7223
7225
7235
7237
7253
7255
7273
7277
7325
7327
7333
7337
7355
7357
7373
7375
7523
7525
7535
7537
7553
7555
7573
7577
7723
7727
7733
7735
7753
7757
7775
7777
|
|
Posted by Charlie
on 2024-12-09 14:38:05 |
computer solution (spoiler)
