Sometimes there’s a connection between numbers and words other than the fact that we use words to give names to numbers. The concept of one is meaningless unless there’s a commonly-understood word that can be used to refer to that concept. If you took a mathematics class in primary or secondary school, you’ll probably remember “story problems” that used many words to present you with an arithmetic problem to solve. Because these problems used words to describe the mathematical concepts, you’d be lost without a good vocabulary to understand all of the words.

When the words for numbers enter into everyday language, they often add more idiomatic meanings. If you’re learning English as a second language, idioms and similar phrases might be confusing, because the words sometimes don’t match their more common, literal definitions (read more about idioms here and here). Today we’ll look at number-related idiomatic phrases and their explanations:

all for one and one for all
The Latin phrase unus pro omnibus, omnes pro uno has been translated into many languages, and might be most famously associated with the comrades Athos, Porthos, Aramis, and d’Artagnan, the Musketeers of the Dumas novel. It’s also the unofficial motto of Switzerland. When you use this idiom, you’re referring to the importance of working together and staying loyal to each other.

kill two birds with one stone
This refers to the act of achieving two different goals with one action. Related phrases are found in ancient Greek and Chinese literature, but we don’t know of any historical event that would have given rise to this expression.

third time’s a charm
The number three has long been associated with spiritual or magical significance (the Holy Trinity of Christianity, for example, or the repetition of chants done three times in rites and ceremonies). You might say this if you’ve tried to do something twice but not succeeded. It’s both a wish and a “good luck charm” that on the third try, everything will work out.

the four corners of the world
You might be wondering how the globe-shaped Earth can have corners, but remember that for a long time, people thought the world was flat, and were depicting it using mostly four-sided maps.

take five
This common expression, short for take a five-minute break, is one that frequently confuses new English speakers. “Take five what?” they ask themselves. When you’re learning a new language, it’s important to pay attention to slang and idiom, otherwise you’ll quickly lose track of the conversation.

at sixes and sevens
This phrase has been used since the mid-14th century to describe being confused or disorganized. In general, it’s used more in the UK than the US.

to be behind the eight ball
People who play the game of pool will immediately recognize that when it’s your turn and the cue ball is stuck behind the eight ball – the ball you can’t hit directly during most of the game – you’re in a bad situation, and that’s the origin of this expression.

a stitch in time saves nine
This is one of the oldest number-related expressions in the English language, and dates back to the days when people had to do their own sewing and mending. If you see a hole in your shirt, it’s best to fix it while it’s small (that is, taking one stitch “in time”) so that you don’t have a larger rip to sew up later (taking nine or more stitches). Today we use this expression to say that it’s better to fix a problem while it’s small than wait until it gets larger.