This shows the billion cube on the far left, with the same human figure to scale (the picture above it is the cut-out indicated by the red rectangular border. Still, “as big as you are” definitely holds, per unit volume! The average volume of an adult human, measured by water displacement, is $66,400 cm^3$…almost 1/200th (0.005) of the million cube! So, not quite as tall as they are: WolframAlpha's growth curves show that the average 7-year old male is already ~40 inches tall). Here's a 174 cm (~5'7”) tall figure to scale with the 1 cm3 base ten block. In case the file doesn't load, here's a few cut out zoom shots to demonstrate:

Here it is, in all it's glory (click to zoom: it's massive): Students always ask, “how big do you think that would be” and, try as I might, they never seem satisfied with my answer (“bigger than you are”)! So I made a huge picture to illustrate what happens if you used these base ten blocks to build up to a billion. He said, after another pause “10 hundred thousand?” I said well, when you have 10 hundred thousands, what do you actually have? You know 700 thousand, 800 thousand, 900 thousand… right? What's next? “1 million!” he said triumphantly. Good, so we just need ten of these flats each flat is worth 100 thousand, so 10 of them is how much. First, we need to build a “long” from these, so how many 1000-cubes do we need? “10.” Good, now, 10 of these 1000-cubes is how many units total? He said, “10 thousand?” I said, yes, exactly! Now that we have a long made of 1000-cubes, how many longs do we use to make a flat? He said, “10.” OK, great! Each flat is how many longs? He said, “10.” And each long is how many 1000-cubes? “10.” So 10 tens makes how many 1000-cubes? He said, “100 1000-cubes!” Awesome! How many units is that? He said (after a pause) “100,000 units”. I told him to imagine that we now take the big 1000-cube and pretend it's the unit cube. I really wanted to show him, but we only have one “block” (the big $1000 cm^3$ cube) and saying “1000 times as big as this” really doesn't cut it. One child asked me the other day how big $1,000,000$ would be using these blocks. For instance, start with the “unit” (1), multiply it by 10 to get the “long” (10), multiply that by 10 again to get the “flat” (100), multiply that by 10 again to get the “block” (1000)… I work as a mathematics tutor with K-12 kids at all ability levels we use these blocks as a visual aid to understanding extremely important mathematical concepts such as counting, thinking in groups, place value, the base-10 system, and even exponents. The smallest discrete unit is $1 cm^3$ and represents the one's place: 10 of these singletons form a stick (sometimes called a “long”) of $10 cm^3$ that represents the ten's place, 10 “longs” make a “flat” of $100 cm^3$ representing the hundred's place, and 10 “flats” make the largest commercially sold denomination, the big cube of $1000 cm^3$ (called a “block”) representing the thousands place.

In case any of my readers do not meet the above criterion, these blue (sometime orange) plastic blocks are manipulatives used in classrooms to help teach kids all sorts of mathematical concepts, from addition and subtraction to place value and volume.

Everybody who went to public elementary school in the USA after the mass production of plastics (1940s and 1950s) and before, say, the advent of the iPad, knows what these things are:

Tens cubes