The LessonAn odd number is a whole number that cannot be divided exactly by 2.
Dictionary DefinitionThe Oxford English Dictionary defines an even number as a number "having one left over as remainder when divided by two. Opposed to even."
Examples of Odd NumbersSome examples of odd numbers are given below:
Odd Numbers on a Number LineThe image below shows the odd numbers on the number line.
How to Check if a Number Is an Odd NumberA number is odd if it cannot be divided exactly by 2. If it is divided by 2, the answer will not be a whole number. There will be a remainder of 1.
QuestionIs 25 an odd number?
Divide the number by 2.
25 ÷ 2 = 12.5 = 12 r 1
Check if the answer from Step 1 is a whole number. If it is not, and there is a remainder of 1, the original number is odd. Else it is even. In our example, 12.5 is not a whole number.
Answer:25 is an odd number.
A Formula to Generate Odd NumbersThe formula below generates odd numbers:
If k takes a whole number (1, 2, 3...), then n will always be odd.
k = 0 ∴ n = 2k + 1 = 2 × 0 + 1 = 1
k = 1 ∴ n = 2k + 1 = 2 × 1 + 1 = 3
k = 2 ∴ n = 2k + 1 = 2 × 2 + 1 = 5
k = 3 ∴ n = 2k + 1 = 2 × 3 + 1 = 7
k = 4 ∴ n = 2k + 1 = 2 × 4 + 1 = 9
Interactive Game on Odd Numbers
- You are the fish.
- Pop the bubbles with odd numbers to collect red hearts. You need five to win.
- If a bubble with an odd number reaches the top, you will lose a red heart.
- Avoid the bubbles with even numbers. If you pop one, you will lose one of your three lives.
- Good luck!
- The fish moves to wherever you taptowards your mouse clicks. (Hint: The farther the distance, the faster it moves.)