The Question
A brilliant number is defined as a natural number that is the product of just two primes, both of which have the same number of digits in base 10.
For example, 15 (=3x5) and 35 (5x7) are 2-digit brilliant numbers but 33 (=3x11) is not; 143 (=11x13) is a 3-digit brilliant number.
Find the smallest and the largest 4-digit brilliant numbers.
This is at the level of a lower secondary national mathematics competition.
Try to share your method so as to help each other learn new techniques and strategies.
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