Some commonly accepted figures useful for making approximations
| Official Population of the US in 2000: | 281 million |
| Official Population of Illinois in 2000: | 12.4 million |
| Official Population of Chicago in 2000: | 2.9 million |
| Average size of a household in the US: | 2.7 people |
| Distance across the US: | about 3000 miles |
| Circumference of the earth: | about 25,000 miles |
| Height of highest mountain (Mt. Everest): | about 29,000 ft. |
| Average distance to the moon: | about 240,000 miles |
| Average distance to the sun: | about 93 million miles |