Wait... today is my birthday!
Number Theory
Level
pending
Today, April 20, 2015, is a very special day. It's my birthday! Let me share a problem with you:
What is the smallest number divisible by the numbers 1 to 7?
The answer is 420.
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1 solution
Happy Birthday!
Well, the answer is 420, or 4/20 as in the date. How funny. Now on the the solution.
Let's list he prime factors for the numbers 1 through 7.
Now, let's combine these. We will only take each number once.
2, 2, 3, 5, 7
But why two 2s?
We need two 2s because in order to make a four, we need two 4s.
When you multiply these numbers out, you get 420.