On the last day of A.D. 2023 my friend W.G. asked me to provide a 4 digit number, which after erasing its second digit (from the left) becomes 1/7 of its original value.
No big deal, I did it on the spot, but in return told him that this number can be defined by some other features and then we have jointly agreed upon at least 2 short descriptions.
I leave it to you :
1. To find the number
2. To provide some not-too-long definitions
1050 = 7*150
So, the four digit number is 1050.
It is equal to 5 times the product of the first four prime numbers, also the product of the nonzero digits(5) and the product of the first 4 prime numbers, since:
1050 = product of the nonzero digits"(2"3*5*7)= 5(2*3*5*7)
Also, sum of the digits =6
Product of the nonzero digits = 5
Then,
1050 = 35* (sum of the digits)*(product of the nonzero digits)
= 5*7*6*5
Incidentally, 35=5*7, so that 35 is the product of twin primes.
Edited on January 3, 2024, 9:45 am
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