I used to believe that rounding a number meant drawing a circle around it.
A childhood belief about classes

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 believed there were little men in my etch a sketch that did the drawing— now a mom
- Until I was about 8 I believed that your back teeth keep growing in until you have a full circle of teeth.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