Lesson 2.1Math~35 min

The number line

Negatives, decimals, distance, and why squaring a number makes it positive.

Module 2 · 0/9 done

Numbers are places

Forget sums for a moment. Picture an endless straight road with a signpost marked 0. Every number is a spot on that road: positive numbers are to the right of 0, negative numbers to the left. This picture is called the number line, and it will quietly sit underneath every chart in this course.

Fig 2.1Drag the point. Decimals live between the whole numbers; negatives are mirror images of positives.

Negative numbers aren’t exotic — they’re temperatures below freezing, money you owe, or a prediction that came out too low. And decimals like 2.5 simply sit between their neighbours.