Q: Is 315,487 a Fibonacci Number?

 A: No, the number 315,487 is not a Fibonacci number.

How is 315,487 not a Fibonacci number?

The Fibonacci Sequence is a series of numbers where you add the previous two numbers together. The product of each is a Fibonacci number.

You start with 0 and add 1 to get the answer 1. You then add 1 + 1 to get 2. Then 2 + 1 to get 3. Then 2 + 3 to get 5, and so on.

To help you see it a little better, the numbers you add together have been color coded:


0 + 1 = 1
1 + 1 = 2
1 + 2 = 3
2 + 3 = 5
3 + 5 = 8
5 + 8 = 13


What would be the next Fibonacci number? If you answered 21, you're right. Here's how: You add 8 + 13, which equals 21. The product of each set of numbers is a Fibonacci number. There are an infinite number of Fibonacci numbers.


So now that we have a little background on what a Fibonacci number is, let's work through it and try to see if 315,487 is a Fibonacci number.


Remember, we start with 0 + 1 = 1 then 1 + 1 = 2 then 1 + 2 = 3 then 2 + 3 = 5, and so on...


Long Form Fibonacci Test


0 + 1 = 1
1 + 1 = 2
1 + 2 = 3
2 + 3 = 5
3 + 5 = 8
5 + 8 = 13
8 + 13 = 21
13 + 21 = 34
21 + 34 = 55
34 + 55 = 89
55 + 89 = 144
89 + 144 = 233
144 + 233 = 377
233 + 377 = 610
377 + 610 = 987
610 + 987 = 1,597
987 + 1,597 = 2,584
1,597 + 2,584 = 4,181
2,584 + 4,181 = 6,765
4,181 + 6,765 = 10,946
6,765 + 10,946 = 17,711
10,946 + 17,711 = 28,657
17,711 + 28,657 = 46,368
28,657 + 46,368 = 75,025
46,368 + 75,025 = 121,393
75,025 + 121,393 = 196,418
196,418 + 317,811 = 317,811

Notice the last equation above (in red). This shows that 315,487 is NOT a Fibonacci number because the sum of the last equation is larger than the number 315,487 and the sum of the equation before it is smaller than the number 315,487.

  • This is just one way to find a Fibonacci number and is arguably the easiest to understand. There are many ways to calculate a Fibonacci number. Take a look at Wikipedia for more information.

More Examples

Here are the next few Fibonacci numbers for you to take a look at:

317,811 514,229 832,040 1,346,269 2,178,309 3,524,578

Are any of the surrounding numbers a Fibonacci number?

Let's take a look and see...

Number 315,485315,486315,488315,489
Fibonacci? nononono

Explore more about the number 315,487:


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