Problema Solution
Find the sum of those numbers between 1000 and 6000 every one of whose digits is one of the numbers 0, 2, 5 or 7. Give your answer as a product of prime numbers.
Answer provided by our tutors
The numbers are 2057, 2075, 2507, 2570, 2705, 2750, 5027, 5072, 5207, 5270, 5702, 5720
The sum = 2057+...+5720 = 46662 = 2*3*7*11*101
So the sum is 46662 = 2*3*7*11*101