Mathematics
Grade 7
15 min
Decimal number lines
Decimal number lines
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1
Introduction & Learning Objectives
Learning Objectives
Identify the value of a point on a decimal number line.
Accurately plot given decimal numbers on a number line.
Construct a decimal number line with an appropriate scale for a given set of numbers.
Compare and order decimal numbers using a number line.
Understand the concept of density of decimals on a number line.
Determine the interval value between tick marks on a decimal number line.
Ever tried to measure something super precisely, like the length of a tiny bug or the exact amount of sugar for a recipe? 📏 Decimals help us with precision!
In this lesson, you'll learn how to use number lines to visualize and understand decimal numbers. This skill will help you compare, order, and make sense of decimal values in a clear, visual way, building a str...
2
Key Concepts & Vocabulary
TermDefinitionExample
Decimal NumberA number that includes a whole number part and a fractional part, separated by a decimal point. The fractional part represents tenths, hundredths, thousandths, etc.3.14 (three and fourteen hundredths), 0.5 (five tenths)
Number LineA straight line on which every point corresponds to a real number. It helps visualize the order and relative values of numbers.A line with marks for 0, 1, 2, 3, and so on, extending infinitely in both directions.
IntervalThe space or distance between two consecutive tick marks on a number line. Each interval represents a consistent value.On a number line marked 0, 0.1, 0.2, the interval between 0 and 0.1 is 0.1.
Tick MarkThe small lines drawn on a number line to indicate specific numerical values. They help divide the line int...
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Core Formulas
Number Line Direction Rule
Numbers on a number line always increase in value from left to right.
This rule helps us understand the relative size of numbers. A number to the right of another is always greater, and a number to the left is always smaller. This applies to whole numbers, integers, and decimals alike.
Consistent Scale Rule
All intervals (the space between consecutive tick marks) on a number line must represent the same value.
To accurately represent and compare numbers, the 'jump' from one tick mark to the next must always be consistent. For example, if one interval is 0.1, all other intervals must also be 0.1.
Identifying Decimal Values Rule
To find the value of an unmarked point or tick mark, determine the scale of the number line and count from...
5 more steps in this tutorial
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Challenging
On a number line, Point A is at 4.4 and Point B is at 4.7. Point C is exactly halfway between A and B. Point D is exactly halfway between C and B. What is the value of Point D?
A.4.55
B.4.6
C.4.625
D.4.65
Challenging
A number line is constructed with tick marks at every interval of 0.06. If one tick mark is labeled 5.42, which of the following values will also be on a tick mark?
A.5.54
B.5.50
C.5.60
D.5.70
Challenging
A student needs to plot the decimals 0.2, 0.7, and 0.75. Why would choosing a scale with intervals of 0.1 be less appropriate than a scale with intervals of 0.05?
A.scale of 0.1 cannot show the number 0.2.
B.scale of 0.1 makes the number line too long.
C.scale of 0.1 is too small to be useful.
D.scale of 0.1 would require estimating the position of 0.75.
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