From the Archives: How Quickly Large Our Numbers Grow

How Quickly Large Our Numbers Grow

On a recent test a student who either did not understand the question or the concept gave an answer that has set me to thinking. Some of these thoughts get philosophical pretty soon.

The question was “How many bits are needed to store 1,024 distinct values?” and the expected response was “Ten.” However, this student wrote “8192.” Clearly, 28192 is a huge number. A very huge number. An astronomically large number, so much so that it is hard to get one’s head around it.

How can we conceive of numbers so large, or how can we relate to them? A quick Internet check tells me a single grain of sand weighs 3 micrograms. That is,

1 grain of sand = 3 × 10^(-6) grams

and if my calculator is correct, 28192 = 1.0907 × 102466; that is,

2^(8192) = 1.090748135619415929462984244733782862448264161… × 10^(2466)

so if we had 28192 grains of sand, that would be around

3.272244406858247788388952734201348587344792483… × 10^2460 grams

and converting that to kilograms gives us it would be

3.272244406858247788388952734201348587344792483… × 10^410 kilograms

Hmm. 3.27 × 10410 kg. I still can’t get that in my mind. Surely, it must be bigger than the sun? Looking up the mass of the sun and finding

mass of the sun = 1.98892 × 10^30 kilograms

we see that

2^8192 grains of sand = 1.6452368153863643527084813538007303397546369300… × 10^380 suns

Let’s state that again: 28192 grains of sand would be about the size of 10380 suns! Not, “more than the mass of the entire solar system,” but much, much more than the entire solar system.

Even with such a comparison, the immense size of such a number is hard to comprehend. But wait a minute! 8,192 bits is 1,024 bytes or 1 kilobyte. How big is that, in today’s world of computers? The laptop computer I carry around has 3 GB of main memory, and a 380 GB internal hard drive.

If 28192 is such a big number it’s hard to comprehend, what about 23,000,000,000 or 2380,000,000,000. How big would those numbers be?

And it’s not even a very powerful computer.