Problem 42 Coded triangle numbers
Problem 42: Coded triangle numbers
The nth term of the sequence of triangle numbers is given by, tn = ½n(n+1); s[……]
Problem 32 Pandigital products
Problem 32: Pandigital products
We shall say that an n-digit number is pandigital if it makes use of all the dig[……]
Problem 23 Non-abundant sums
Problem 23: Non-abundant sums
A perfect number is a number for which the sum of its proper divisors is exactly e[……]
Problem 1 Multiples of 3 and 5
Problem 1: Multiples of 3 and 5
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get[……]