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Number - Introduction to Fractions

Grade 3IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

A fraction represents a part of a whole object or a group that has been divided into equal pieces. For example, if a circular pizza is cut into 44 equal slices and you take 11, you have 14\frac{1}{4} of the pizza. Visually, this looks like one shaded wedge in a circle divided into four equal parts.

The Numerator is the top number in a fraction that tells us how many equal parts are being shaded or counted. In the fraction 23\frac{2}{3}, the number 22 is the numerator, meaning we are looking at two specific pieces.

The Denominator is the bottom number that tells us the total number of equal parts the whole is divided into. If a square is divided into 44 smaller equal squares, the denominator is 44. A larger denominator means the whole is divided into more, smaller pieces.

Unit Fractions are fractions where the numerator is always 11, such as 12\frac{1}{2}, 13\frac{1}{3}, or 110\frac{1}{10}. They represent exactly one part of the whole. On a number line from 00 to 11, 12\frac{1}{2} is located exactly in the middle.

Fractions must consist of equal-sized parts. If a shape is divided into parts that are not the same size, they cannot be accurately named using a simple fraction. For instance, a rectangle split into one huge piece and one tiny piece is not divided into halves.

Fractions can be shown on a number line. The distance between 00 and 11 is treated as the 'whole.' If the line is divided into 55 equal intervals, each tick mark represents a multiple of 15\frac{1}{5}, starting from 15,25,35\frac{1}{5}, \frac{2}{5}, \frac{3}{5} and so on.

Comparing fractions with the same denominator is simple: the fraction with the larger numerator is the greater fraction. For example, 56>26\frac{5}{6} > \frac{2}{6} because 55 equal parts of a bar are more than 22 parts of the same sized bar.

Fractions can also describe a part of a set. If you have a collection of 88 marbles and 33 of them are green, then 38\frac{3}{8} of the set of marbles is green.

📐Formulae

Fraction=Numerator (Part)Denominator (Whole)\text{Fraction} = \frac{\text{Numerator (Part)}}{\text{Denominator (Whole)}}

Unit Fraction=1n (where n is the number of parts)\text{Unit Fraction} = \frac{1}{n} \text{ (where } n \text{ is the number of parts)}

Whole=nn=1\text{Whole} = \frac{n}{n} = 1

💡Examples

Problem 1:

Sarah divides a chocolate bar into 88 equal pieces. She gives 33 pieces to her friend. What fraction of the chocolate bar did she give away, and what are the numerator and denominator?

Solution:

Step 1: Identify the total number of equal parts, which is 88. This is the denominator. Step 2: Identify the number of parts given away, which is 33. This is the numerator. Step 3: Write the fraction as 38\frac{3}{8}.

Explanation:

The denominator 88 represents the whole bar divided, and the numerator 33 represents the parts Sarah shared.

Problem 2:

Look at a number line between 00 and 11. If the line is divided into 44 equal segments, what fraction represents the point at the 3rd3^{rd} tick mark after 00?

Solution:

Step 1: Count the total number of equal segments between 00 and 11, which is 44. This is our denominator. Step 2: Locate the 3rd3^{rd} mark, which indicates 33 segments have been counted. This is our numerator. Step 3: The fraction is 34\frac{3}{4}.

Explanation:

On a number line, the denominator is the total number of spaces between whole numbers, and the numerator is how many spaces we have moved from zero.