GeekDad Puzzle of the Week Solution: Bigger Than Googol!

Geek Culture

Max, happy with the number of solutions submitted

As my son Max and I sat together at his 5th birthday party (natal anniversary party) this weekend, we discussed higher math and how it was going to help him take over the world. After walking him through Fibonacci numbers, and talking about really big numbers, he asked me a simple question with a not so simple answer: What is the first Fibonacci number bigger than a googol?

Using estimation techniques, we can guess or identify answer’s count/sequence number. The winning answer to this week’s puzzle will include both the sequence number and the value.

Solution: There were a lot of solutions presented this week, more than 3x what we have seen in previous weeks. I attribute this to the “Max plotting to take over the world image” (left) but it could also be because it was a somewhat intricate puzzle that is simple to state. That having been said, it is also the case that there were a lot of incorrect answers submitted as well.

The correct answer is F481, the first Fibonacci number with 101 digits. Yes, 101 digits, as a googol is defined as a 1 followed by one-hundred (100) zeros — meaning it has 101 digits. F481 is precisely
14,913,169,640,232,740,127,827,512,057,302,148,063,648,650,711,209,401, 966,150,219,926,546,779,697,987,984,279,570,098,768,737,999,681. There were several solutions presented that, while correctly identifying F481, listed the number only out to 12 or 18 significant digits, i.e., 1.491317… x 10100. Additionally, there were several Excel-based solutions that presented a full 101 digits, but similarly lacked precision: F481 is not 14,913,169,640,232,700,000,000,000,(lots of zeros),000,000!

Congratulations to Torben Rybner, this week’s winner of this week’s $50 ThinkGeek gift certificate. For those of you not fortunate enough to be Torben (aren’t we all) and are still big shoppers at ThinkGeek (once again, aren’t we all!) please take advantage of their $10 off a $50 order offer by using GEEKDAD37MD when you check out.

Have a great week, and enjoy the upcoming geeky holiday on Wednesday!

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