by Victor Bryant
Published September 15 2019 (link)
I have written down four different numbers. The third number is the highest common factor of the first two (ie it is the largest number that divides exactly into both of them). The fourth number is the lowest common multiple of the first two (ie it is the smallest number that both of them divide exactly into).
I can consistently replace digits by letters in my numbers so that the highest common factor is HCF and the lowest common multiple is LCM.
What are the first two numbers?