simple arithmetics

[kemioli]

Write a java program to calculate how many the numbers lie
between 50 and 257 and are divisible by 3

you may use the if-else and for loop constructs.
Help out please!!

[acoder]

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[mrhoo]

First, make an array of the numbers in your range that are not prime,
and then divide the rest by 3 and remove the ones with remainders.

This function finds primes, you can do the rest.

function getPrimes(limit,startN){
    if(limit>1000000){
        var str='Better make coffee while this runs, '+
        'or "cancel" and pick a smaller number';
        if(!confirm(str))return false;
    }
    var n= limit, numberA=[], pA=[],limN,j=2;
    startN= startN ||  0;
    for (var  i= 2; i<= n; i++) numberA[i]= true;
    limN= Math.sqrt(n);
    for (var i= j+j; i<n; i= i+j) numberA[i]= false;
    for(j= 3; j<= limN; j= j+2){
        if(numberA[j]) for (i= j+j; i<n; i= i+j) numberA[i]= false;
    }
    for (i= startN; i< n; i++) if(numberA[i]) pA.push(i);
    return pA;
}