Programming Trick's

Get Missing number from the list.
//return value will be the missing number.
static int getMissingNo(){
int [] a = {1,2,4,5,6};
int total = (a.length+1) * (a.length + 2)/2;
for(int i = 0; i< a.length;i++){
total -= a[i];
}
return total;
}

Print the Prime numbers upto N number .
void primes(int n){
int primes[] = new int[105];
for(int i=0;i