20% Discount Primes
Computer Science
Level
3
How many five-digit primes have exactly one zero as a digit?
For example, 984 0 7 is one such prime.
The answer is 2017.
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1 solution
The following C program will find and count all such prime numbers, #include<stdio.h> int checkprime(int); main() { int j=0,flag2,i,k,c; for(k=10000;k<=99999;k++) { c=checkprime(k); if(c==1) { flag2=0; i=k; while(i) { c=i\%10; i=i/10; if(c==0) { flag2++; } } if(flag2==1) { printf("\%d\n",k); j++; } } } printf("\nNo.of such numbers is \%d\n",j); } int checkprime(int a) { int i,flag=0,c; for(i=2;i<=(a/2);i++) { if(a\%i==0) { flag=1; return 0; } } if(flag==0) return 1; }