
This is a drawing of Albert Einstein I drew when I was in 9th standard.
73939133: I came across this fact. This is really cool. The specialty of this number is not just that it is a prime number but, every number that is produced by removing the last digit one by one is also a prime number. So, the following numbers are all prime.
7393913
739391
73939
7393
739
73
7
This is the largest such number known (as of today).
There is an interesting theorem in Mathematics. It states that every number is an interesting number. The proof is as follows and is based on the principle of mathematical induction:
One is interesting because it is the first natural number. Two is interesting because it is the first even number. Three is interesting because it is the first odd prime number. Let us now assume that the first ‘n’ numbers are interesting so that ‘n+1’ can possibly be uninteresting. But, this number will also be interesting as it is the first uninteresting number. Hence, by the principle of mathematical induction the all natural numbers are interesting.