Stem-and-Leaf Diagrams

A stem-and-leaf diagram sorts a list of numbers while keeping every value. Each number is split into a stem (the leading digit or digits) and a leaf (the last digit). For example 23 splits into stem 2 and leaf 3. The leaves are written in order next to their stem, so numbers sharing a stem line up in one row.

Take the data 12, 15, 21, 23, 23, 34, 38. The tens digit is the stem (1, 2, 3) and the units digit is the leaf. Writing each leaf in order gives:

Stem	Leaf
1	2 5
2	1 3 3
3	4 8

Every diagram must include a key so the reader knows the place value of the digits:

Key: 2 \mid 3 means 23.

Reading along the rows recovers the sorted data exactly: 12, 15, 21, 23, 23, 34, 38 — nothing is lost.

Split each number into a stem (leading digits) and a leaf (last digit).
Write the leaves for each stem in order, smallest first.
Always give a key (e.g. 2 \mid 3 means 23) to fix the place value.
Because the diagram keeps the raw data, you can read off the mode (most repeated leaf), the median (middle value) and the range (largest − smallest) directly.