Number Line and Comparing Numbers

A number line is a straight line where numbers are placed in order.

• Zero is at the center, it is called the origin.
• Numbers to the right of 0 are positive numbers (1, 2, 3, …).
• Numbers to the left of 0 are negative numbers (-1, -2, -3, …).

✅ Key Facts of a Number Line:

• The further right you move, the bigger the numbers get.
• Numbers are spaced at equal intervals on the line.
  • The gap between numbers can be 1, 10, 100, or any amount, but it must stay the same across the whole line.

Inequality symbols are used to compare two numbers or quantities.

• Greater than ($>$):
  Example: $20 > 12$ (20 is greater than 12)

• Less than ($<$):
  Example: $20 < 38$ (20 is less than 38)

• Greater than or equal to ($\geq$):
  Example: $20 \geq 12$ (20 is greater than or equal to 12)

• Less than or equal to ($\leq$):
  Example: $20 \leq 20$ (20 is less than or equal to 20)

  • This means 20 is either smaller than or exactly equal to 20. Since 20 equals 20, the statement is true.

💡 Tip to Remember Inequality Symbols 

The crocodile’s mouth always opens towards the bigger number, as it wants to eat the larger number!

When comparing positive numbers, follow these two simple rules:

🌟 Rule 1: Look at the number of digits

• A number with more digits is always greater.
• Example: $1001 > 998$ (1001 has 4 digits, 998 has 3 digits.)

🌟 Rule 2: Compare digits from left to right

• If the numbers have the same number of digits, compare each digit one by one, starting from the left.
• The first bigger digit you find decides which number is greater.
• Example: $6749 < 6784$ (Compare: 6 = 6, 7 = 7, 4 < 8 → so 6749 is smaller than 6784. The rest digits do not matter.)