Odd and Even Numbers

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Suppose you are given a box of candies. Your friend asks you to share with him equally. Will both of you be getting an equal number of candies? Will you or your friend get one extra candy when you share? On what basis do you share them? Let us learn how to solve this situation.

A set of objects that can be split into two equal groups is referred to as an even numbered set. For example, 6 bananas can be split into two groups having 3 bananas in each group. Refer to the image given below.

Splitting set of objects
Splitting set of objects

A set of objects that cannot be split into two equal groups and whenever it is split, one group will have one number more than the other is referred to as an odd numbered set. For example, 9 oranges can be split into two groups having 5 oranges in one group and 4 oranges in the other. Refer to the image given below.

Splitting set of objects
Splitting set of objects

Let us consider a number line. Numbers 0 to 9 can be split into two groups as pictured. Numbers 1, 3, 5, 7, and 9 are odd numbers; numbers 0, 2, 4, 6 and 8 are even numbers.

Odd and even numbers marked on the number line
Odd and even numbers marked on the number line

We can also notice that alternative numbers are odd and even. That is, after every odd number there will be an even number; after every even number there will be an odd number.

Odd and even numbers marked on the number line with positive and negative numbers
Odd and even numbers marked on the number line with positive and negative numbers

The number line shown below represents the plot of only even numbers.

Plot of even numbers
Plot of even numbers

While this second number line below shows the plot of only odd numbers.

Plot of odd numbers
Plot of odd numbers

How do you know a number is an even or an odd?

We can know whether a number can be split into two equal groups or not, based on the digits in the “Ones” place. Therefore, looking at the ones place of a number we can identify a multi-digit number to be even or odd.

In a number (of any digits), check for the digit at the ones place. The digit at Ones place decides whether the number is odd or even.

If the numbers ending with the digits 0, 2, 4, 6 or 8, then such numbers are even. For example, 1354 is an even number as the digit in ones’ place is 4.

If the numbers ending with the digits 1, 3, 5, 7 or 9, then such numbers are odd. For example, 1465 is an odd number as the digit in ones’ place is 5.

Example 1: Identify whether the following numbers are odd or even.
25, 63, 84, 62, 128, 351

Solution: (Recall the definitions of odd and even numbers.)
Odd numbers: 25, 63, 351 (Digits at ones place are odd.)
Even numbers: 84, 62, 128 (Digits at ones place are even.)

Activity 1

Click and answer to identify if there are odd or even number of objects.

Practice problems to understand odd and even numbers
Practice problems to understand odd and even numbers

Chart of Odd and Even Numbers 1 – 100

In this chart, all the numbers in the blue rows are odd numbers and all the numbers in the white rows are even numbers.

Odd and even numbers chart
Odd and even numbers chart

Math Facts

  • The sum of two odd numbers is always even.
  • The sum of two even numbers is always even.
  • The sum of an odd and an even number is always odd.
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    Know more about other concepts of Number Sense on Cardinality, Rounding Numbers, Comparing Numbers, Ordinal Numbers and Counting Numbers