The way the article uses RSA is no better than a simple substitution cipher. Both the "l"s in "hello" are enciphered to 2575. It's a newspaper cryptogram.
You're supposed to concatenate all the input numbers, to create a message that has hundreds or thousands of digits; then RSA-encrypt that number.
You're supposed to concatenate all the input numbers, to create a message that has hundreds or thousands of digits; then RSA-encrypt that number.