Decimal number line
A decimal number line divides each unit interval into ten equal parts of 0.1 each in Grade 6 math (Saxon Math, Course 1). On a number line between 0 and 1, the marks at 0.1, 0.2, 0.3, …, 0.9 represent tenths. Between 0.1 and 0.2, further divisions show hundredths (0.11, 0.12, …). Decimal number lines make decimal ordering and comparison visual: 0.6 > 0.3 because 0.6 is further right. They also show that between any two decimals, infinitely many others exist. This concept reinforces place value understanding and bridges whole number number line skills to the full rational number line used in later mathematics.
Key Concepts
Property On a number line, the distance between consecutive whole numbers can be divided into ten equal lengths. Each length is $\frac{1}{10}$ of the distance between consecutive whole numbers.
Examples An arrow points to the eighth mark after the whole number 3, which represents $3\frac{8}{10}$ or 3.8. An arrow points to the second mark after the whole number 9, which represents $9\frac{2}{10}$ or 9.2. An arrow points to the fifth mark after the whole number 6, which represents $6\frac{5}{10}$ or 6.5.
Explanation Imagine a ruler where the space between whole numbers is chopped into 10 equal bits called tenths. Each tiny bit is worth $\frac{1}{10}$, or 0.1. So, if you start at the number 5 and hop over 4 of these tiny marks, you land on $5\frac{4}{10}$. We just write this in its cool decimal form: 5.4! It’s that simple.
Common Questions
How is a decimal number line constructed between 0 and 1?
Divide the unit from 0 to 1 into 10 equal parts. Each part is 0.1 (one-tenth). Label marks at 0.1, 0.2, 0.3, ..., 0.9.
How do you locate 0.35 on a decimal number line?
Find the space between 0.3 and 0.4. Divide it into 10 equal parts. Count 5 parts from 0.3 to reach 0.35.
How do you use a decimal number line to compare 0.4 and 0.6?
0.6 is to the right of 0.4, so 0.6 > 0.4.
What fraction does each small mark on a decimal number line represent?
Each mark between whole numbers represents 1/10. If the interval is divided into hundredths, each smaller mark represents 1/100.
Can you plot negative decimals on a decimal number line?
Yes. Extend the number line to the left of zero. −0.5 is halfway between 0 and −1.