It always seems like textbooks like to teach you a topic, give an extremely easy example problem and then give you a twist on your homework problems. Trying to understand a Stem and Leaf Plot with Decimals is one of these tricks. The example is easy, everything is in order and fits nicely, and then there’s a twist.
Luckily decimals really don’t make stem and leaf plots THAT much more difficult. You begin with the same steps as regular problems. If the numbers in the group aren’t already in order, you still have to list them in order, smallest to largest. Then we know the leaves will be the digit on the far right of each number. Here is where decimals get tricky.
Decimal Between Stem and Leaf
If you have a number like 12.3 you would make “12” the stem and “3” the leaf. That’s right, the decimal doesn’t even matter. Since the decimal is in the place of the vertical line separating the stem and leaf, we don’t have to worry about it.
So how do you tell the difference between 12.3 and 123? Good question.
The answer lies with the stem and leaf plot key. Especially in stem and leaf plots with decimals, the key is very important, because it shows where the decimal goes. For the example 12.3, the Key would show that 12 | 3 equals 12.3 units.
Decimal In the Stem
Let’s look at a similar example. If we had the number “1.23” and wanted to put it on a stem and leaf plot, we would have to look at it differently. The leaf should only be one digit, so this makes our stem “1.2”. In this case, the decimal DOES show up, since it has a place within the stem. The leaf would simply be “3”.
You should always include a key, even though no one should get this one confused. For nothing else, the key will show what units you are working in. Even though no one will confuse 1.23 with 123, if you left out the key we wouldn’t know if you were talking about seconds, dollars, inches, etc. For this example we would show the key is – 1.2 | 3 equals 1.23 units.
