js联系题目

1.1到100的和

var sum = 0 ;

for(var i = 1; i<= 100; i++){
sum = sum + i;
}
console.log("从1加到100的和:" + sum);

2.6的阶乘

var result = 1;
for(var i = 1; i <= 6 ; i++){
result = result * i;
}
console.log("6的阶乘为:" + result);

3.水鲜花数

var a , b , c;//a为百位，b为十位，c为个位
for(var i = 100; i < 1000; i++){
a = parseInt(i/100);
b = parseInt((i%100)/10);
c = parseInt(i%10);
if (i == a * a * a + b * b * b + c * c * c ) {
console.log("水鲜花数为:" + i);
}
}

4 .取出四位数的每一位数

    var num = 4396;
    var a = parseInt(num/1000);(取出千位)
    var b = parseInt((num%1000)/100);(取出百位)
    var c = parseInt(((num&1000)%100)/10;(取出十位)
    var d = num%10;(取出个位)
    console.log(a,b,c,d);

5.99乘法表

var z = "";
     for(var x = 1; x <= 9; x++ ){
      for(var y = 1; y <= x ; y++){
        z += x + "*" + y + "="+ x * y + " "; 
        }
        z+=" ";
     }
    console.log(z);

6.计算1990到2100之间的闰年

console.log("闰年：")
var result6 = "";
var flag = 0;
for (var year = 1900; year <=2100; year++){
if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
result6 += year +" ";
flag++;
}
if (flag == 5) {
result6 += " ";
flag = 0;
}
}
console.log(result6);

7.1000以内能被5和6同时整除的数

var flag = 0 ;
for(var i = 1 ; i <= 1000; i++){
if(i % 5 == 0 && i % 6 == 0 ){
console.log(i);
}
}

8.1到100之间的素数

var flag;
for(var i = 2; i <100; i++){
flag = true;
for(var j = 2; j<i; j++){
if(i % j == 0){
flag = false;
}
}
if(flag){
console.log(i);
}

9.交换两个数　　

第一种方法

var b = 123 , c = 234 ;
var d;
d = b;
b = c;
c = d;
console.log(b);
console.log(c);

第二种方法

var m = 456 , n = 789;
var m = m + n;
n = m - n;
m = m - n;
console.log(m,n);