Each individual value from the sample of 80 entries (top right) is recorded in the Stem-and-Leaf plot as a combination of two parts—The stem and the leaf. Depending on the choice of the leaf unit—in our case 1—we treat the first digit (the 10s place) as the stem and the second digit (the 1s place) as the leaf. A leaf unit of 1 implies a binning on the stem in 10s, that is, 20, 30, 40, all the way to 110 and 120.
For example the smallest value in the sample is 27. This is read in the Stem-and-Leaf plot on the first row by combining the stem digit "2" and the leaf digit "7". Because we have two "27" entries in the sample in the range 20-30-, we read two "7" in the leaf.
Similarly, the largest number in the sample is 125. This is read on the last row of the chart by combining the stem digit "12" and the leaf digit "5". The second largest number is "122", hence the leaf digit is "2".
Lets build the chart in Excel. The data is in the range B7:B87.