the javascript code:

function isPrime(n){
for (c=2; c<n; c++){
if (n%c == 0) return false;
}
return true;

}

document.write("<table border='2'>");
// creating all cells
for (var j = 0; j < 10; j++) {
// creates a table row
document.write("<tr>");


for (var i = 1; i <= 10; i++)
{
Number= j*10 + i;

if (Number < 3 || isPrime(Number))
{
document.write("<td class='primes'>");
document.write(Number);
document.write("</td>");

}else if (Number % 3 ==0){
document.write("<td class='blue'>");
document.write(Number);
document.write("</td>");

}else if (Number % 7 ==0){
document.write("<td class='green'>");
document.write(Number);
document.write("</td>");
}else if (Number % 2 ==0){
document.write("<td class='gray'>");
document.write(Number);
document.write("</td>");
}else {
document.write("<td>");
document.write(Number);
document.write("</td>");
}

}
}
document.write("</tr>");
document.write("</table>");