2021 JMPSC Accuracy Problems/Problem 14
Problem
What is the leftmost digit of the product
Solution
We notice that
In addition, we notice that
Since
We conclude that the leftmost digit must be .
~Bradygho
Solution 2
By multiplying out ,
, and
, we notice that the first
digits don't change even when we continue to add more digits. With this observation, we can conclude that the first digit of the product is
.
~Mathdreams