I used to think that when you had to give your 'daytime telephone number', it meant that your number would change when people called you at night!
A childhood belief about technology

others believed things like this
- when i was little i believed that your social security number was the number you were born on the earth — christine
- I used to believe that rounding a number meant drawing a circle around it.Anon
- I used to believe there was a number "eleventeen". I could never quite work out where it went, though.— Matthew
- I used to think boys went "number two" with their pee pees. Anon
- I used to believe that twenty was the largest number in the universe.— Bernardo Fernandez
- I used to think that any number with a decimal point in it was HUGE.— sm