Grade 7 ↓
Number System
The number system is an essential foundation for mathematics. It is the way we understand and work with numbers in everyday life and in more advanced mathematical tasks. We are going to understand this in detail, starting with the types of numbers. breaking down and how they interact with each other.
What is the number system?
A number system is a way of representing and working with numbers. It provides a framework for writing numbers, representing quantities, and performing calculations. The most widely used number system in the world today is the decimal system, which is called the decimal number system. Also known as base-10.
Decimal system
The decimal system is called the base-10 system because it is based on ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. Any number can be formed using these digits. For example, 573 is a number where:
573 = 5 × 100 + 7 × 10 + 3 × 1
This system relies on place value, where the position of each digit determines its value. The rightmost digit has the smallest value, often called the units place, and each step to the left increases the value by a power of ten. It increases.
Example:
Number: 4,572 Places: thousands, hundreds, tens, ones Values: 4*1000, 5*100, 7*10, 2*1
Types of numbers
Numbers can be classified into different types. Let's take a look at each type:
Natural numbers
Natural numbers are the numbers we use for counting. They start at 1 and go on to infinity: 1, 2, 3, 4, 5, etc.
Whole numbers
Whole numbers are just like natural numbers, but they include zero. So, the sequence starts with 0. Example: 0, 1, 2, 3, 4, 5, etc.
Integers
Integers include whole numbers and their negative counterparts. This means that the integers are ... -3, -2, -1, 0, 1, 2, 3, ...
Rational numbers
Rational numbers are numbers that can be expressed as a fraction of two integers where the denominator is not zero. For example, 1/2
, -3/4
, and 5/1
(which is just 5) All are rational numbers.
Examples of rational numbers:
1/2, -2/3, 4/5, 7/1, -8/2
Irrational numbers
Irrational numbers are numbers that cannot be written as a simple fraction. This means that their decimal places go on forever without repeating. Common examples include the square root of 2 and π
(pi).
Example:
√2 = 1.414213... π = 3.141592...
Real numbers
Real numbers are all the numbers on the number line, including both rational and irrational numbers. If you can point to a number on the number line, it is a real number.
Operations with numbers
We use many basic operations with numbers. These operations help us perform calculations in real life.
Add
Addition is the sum of two or more numbers. For example, 3 + 7 = 10
.
Subtraction
Subtracting is subtracting one number from another to get the difference. For example, 10 - 4 = 6
.
Multiplication
Multiplication involves adding a number to a certain number. For example, 5 × 3 = 5 + 5 + 5 = 15
.
Division
Dividing means dividing a number into equal parts. For example, 12 ÷ 4 = 3
because 12 divided into 4 equal parts gives 3.
Properties of numbers
Numbers have different properties that can help simplify calculations and understand their behavior.
Commutative property
This property states that the order of numbers can be changed without affecting the result. This applies to both addition and multiplication.
Example:
Addition: 4 + 5 = 5 + 4 Multiplication: 6 × 7 = 7 × 6
Associative property
According to this property, the grouping of numbers can be changed without affecting the result. This also applies to addition and multiplication.
Example:
Addition: (2 + 3) + 4 = 2 + (3 + 4) Multiplication: (1 × 2) × 3 = 1 × (2 × 3)
Distributive property
This property connects addition and multiplication. It states that multiplying a number by a group of numbers added together is the same as doing each multiplication separately.
Example:
a × (b + c) = a × b + a × c 3 × (4 + 5) = 3 × 4 + 3 × 5
Working with decimals
Decimals are another way to represent numbers, which is especially useful for expressing numbers that are not whole. Decimal numbers have a whole number part and a fractional part that are separated by a decimal point.
Example: 3.75
means the whole number 3 and 75 one hundredth (or 75/100).
Working with fractions
Fractions represent parts of a whole. A fraction has a numerator and a denominator, where the numerator is the top part and the denominator is the bottom part of the fraction.
Example: In the fraction 3/4
, 3 is the numerator and 4 is the denominator.
Fractions can also be converted to decimals by dividing the numerator by the denominator. For example:
Converting 1/2
to decimal:
1 ÷ 2 = 0.5
Working with percentages
Percentages are a special way of expressing fractions out of 100. For example, 50% means 50 out of 100 or 50/100, which is the same as 0.5 as a decimal.
Calculation of percentage:
25% of 200 = (25/100) × 200 = 50
Conclusion
Understanding the number system is important not just for mathematics but also for everyday life. Numbers are everywhere, whether we are counting, measuring or doing more complex calculations. Know the different types of numbers and their properties. With a solid understanding, mathematical operations become intuitive and more manageable.