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.
始めの問題だけあって簡単。手計算でできる。
p001 = sum [n|n<-[1..999],mod n 3 ==0||mod n 5==0]