Problem #1
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.
var result = 0;
for (var i = 0; i < 1000; i++){
if ((i % 3 == 0) || (i % 5 == 0)){
result = result + i;
}
}
result
Problem #2
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.
function fib(index){
if (index == 0) {
return 0;}
else if (index == 1) {
return 1;}
else {
return fib(index - 1) + fib(index - 2)}
}
var result = 0;
var index = 0;
while (fib(index) <= 4000000){
if (fib(index) % 2 == 0){
result += fib(index)}
index++;}
result
Problem #3
The prime factors of 13195 are 5, 7, 13 and 29.
What is the largest prime factor of the number 600851475143 ?
var number = 600851475143;
var divisor = 1;
while (number > 1) {
if (number % divisor == 0) {
number = number / divisor;}
divisor++;}
divisor-1
Problem #4
A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
Find the largest palindrome made from the product of two 3-digit numbers.
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