Solved Exercises on Odd and Even Numbers in Grade 1

Master odd and even numbers: identification, classification, and pattern recognition through these 3 detailed exercises.

Solution: Exercises 1 to 3
1 Identifying odd and even numbers
Exercise 1
Circle the even numbers and underline the odd numbers in this list: 7, 12, 15, 20, 23, 28, 31, 36
Definition:

Even numbers: Numbers that can be divided by 2 without a remainder. Odd numbers: Numbers that cannot be divided by 2 without a remainder.

Identification method:
  1. Look at the last digit of each number
  2. If the last digit is 0, 2, 4, 6, or 8, the number is even
  3. If the last digit is 1, 3, 5, 7, or 9, the number is odd
  4. Alternatively, try to divide each number by 2 to check for remainder
Original List
7, 12, 15, 20, 23, 28, 31, 36
Classification
O, E, O, E, O, E, O, E
Result
Even: 12,20,28,36; Odd: 7,15,23,31
Step 1: Examine each number individually

Check if each number can be divided by 2 without remainder

Step 2: Apply the last digit rule

7 (last digit 7) → odd, 12 (last digit 2) → even, 15 (last digit 5) → odd, etc.

Step 3: Classify each number

Even numbers: 12, 20, 28, 36 (can be paired perfectly)
Odd numbers: 7, 15, 23, 31 (have one left over)

Even: 12, 20, 28, 36
Odd: 7, 15, 23, 31
Final answer:

Even numbers: 12, 20, 28, 36
Odd numbers: 7, 15, 23, 31

Applied rules:

• Even numbers: Divisible by 2 with no remainder

• Odd numbers: Not divisible by 2 (remainder of 1)

• Last digit rule: Even numbers end in 0,2,4,6,8; odd numbers end in 1,3,5,7,9

2 Grouping objects into pairs
Exercise 2
You have 13 marbles. Can you put them into pairs with none left over? Explain why or why not.
Definition:

Grouping into pairs: The process of organizing objects into sets of 2 to determine if a number is even or odd

Number of Marbles
13
Pairing Process
13 ÷ 2 = 6 R1
Result
One marble left over
Step 1: Start with 13 marbles

We have 13 individual marbles to work with

Step 2: Form pairs

Make groups of 2: Marble 1 + Marble 2, Marble 3 + Marble 4, etc.

Step 3: Check for leftovers

After forming 6 pairs (12 marbles), 1 marble remains unpaired

13 is odd because 13 ÷ 2 = 6 remainder 1
Final answer:

No, you cannot put 13 marbles into pairs with none left over. There will be 1 marble left over, which means 13 is an odd number.

Applied rules:

• Even numbers: Can be perfectly divided into pairs (no remainder)

• Odd numbers: Cannot be perfectly divided into pairs (remainder of 1)

• Division rule: When dividing by 2, remainder 0 = even, remainder 1 = odd

3 Continuing number patterns
Exercise 3
Continue this pattern of even numbers: 4, 8, 12, 16, ___, ___, ___
Definition:

Number pattern: A sequence of numbers that follows a specific rule or pattern

Given Pattern
4, 8, 12, 16, ___, ___, ___
Rule
Add 4
Completed
4, 8, 12, 16, 20, 24, 28
Step 1: Identify the pattern

Looking at 4, 8, 12, 16 - each number is 4 more than the previous

Step 2: Confirm these are even numbers

All numbers (4, 8, 12, 16) are divisible by 2, confirming the pattern is even numbers

Step 3: Apply the pattern to find the next numbers

16 + 4 = 20, 20 + 4 = 24, 24 + 4 = 28

Step 4: Verify the results

20, 24, and 28 are all even numbers (divisible by 2)

4, 8, 12, 16, 20, 24, 28
Final answer:

The missing numbers are 20, 24, and 28. The complete pattern is: 4, 8, 12, 16, 20, 24, 28

Applied rules:

• Pattern recognition: Identify the consistent operation between consecutive numbers

• Even number pattern: Even numbers increase by 2 (2, 4, 6, 8, 10...) or multiples (4, 8, 12...)

• Consistency: Apply the same operation to find missing values

Visual Infographic: Odd and Even Numbers

Odd and Even Numbers

Understanding Number Classification

1
2
3
4
5
6
7
8
9
10
→
2
Even
3
Odd
4
Even
5
Odd
Even Numbers
Can be divided by 2 without remainder. End in 0, 2, 4, 6, or 8.
Odd Numbers
Cannot be divided by 2 without remainder. End in 1, 3, 5, 7, or 9.
Even Pattern
Increase by 2: 2, 4, 6, 8, 10, 12...
Odd Pattern
Increase by 2: 1, 3, 5, 7, 9, 11...
Rules and methods, laws,...
\(n \div 2 = \text{remainder 0 (even)}\)
Even Number Test
Even
\(n \div 2 = \text{no remainder}\)
Divisible by 2
Odd
\(n \div 2 = \text{remainder 1}\)
Not divisible by 2
Pattern
\(2, 4, 6... / 1, 3, 5...\)
Alternating sequence
Even numbers: Divisible by 2 with no remainder. End in 0, 2, 4, 6, 8.
Odd numbers: Not divisible by 2 (remainder of 1). End in 1, 3, 5, 7, 9.
Key Concepts: Odd and Even Numbers
\(n \mod 2\)
Modulo Operation
Key definitions:

Even number: A whole number that can be divided by 2 with no remainder

Odd number: A whole number that cannot be divided by 2 without a remainder

Number pattern: A predictable sequence following a specific mathematical rule

Complete methodology:
  1. Identify the number: Look at the number you want to classify
  2. Apply the divisibility test: Divide by 2 and check for remainder
  3. Use the last digit method: Check if the last digit is even or odd
  4. Verify with pairing: Imagine grouping objects into pairs
Tip 1: Remember: even numbers end in 0, 2, 4, 6, or 8.
Tip 2: Odd numbers end in 1, 3, 5, 7, or 9.
Tip 3: Practice with physical objects to visualize pairing.
Tip 4: Odd and even numbers alternate: even, odd, even, odd...
Common errors: Misidentifying numbers ending in 0 as odd, forgetting the alternating pattern.
Practice tips: Start with numbers 1-10, then extend to larger numbers.
Key rules to remember:

• Even numbers: Divisible by 2 (remainder 0)

• Odd numbers: Not divisible by 2 (remainder 1)

• Last digit rule: Even numbers end in 0,2,4,6,8; odd numbers end in 1,3,5,7,9

• Alternating pattern: Even and odd numbers alternate in sequence

Questions & Answers

Question: Why do we need to know about odd and even numbers? When will I use this?

Answer: Learning about odd and even numbers is important because it builds foundational math skills! You'll use this knowledge:

  • When learning multiplication and division
  • To understand number patterns and sequences
  • When working with fractions and grouping
  • In real life: sharing items equally with friends

It also helps develop logical thinking and prepares you for more complex math concepts. Plus, it's fun to notice patterns in numbers everywhere!

Question: My child is struggling to understand the concept. How can I make it more tangible for them?

Answer: Making odd and even numbers tangible is key! Try these hands-on activities:

  • Use small toys, blocks, or candies to physically group into pairs
  • Draw circles or dots and connect them in pairs
  • Have your child count steps while walking, calling out "even" and "odd" alternately
  • Use a hundreds chart and color even numbers one color, odd another

The physical act of pairing objects helps children visualize the concept. Once they understand the idea with small numbers, gradually introduce larger numbers.

Question: What about zero? Is it odd or even?

Answer: Zero is an even number! This might seem surprising, but here's why:

Zero can be divided by 2 with no remainder: 0 ÷ 2 = 0 with remainder 0.

You can think of zero as "no groups of two," which still fits the definition of being divisible by 2. Zero also follows the pattern rule - it ends in 0, which is one of the even digits (0, 2, 4, 6, 8).

So remember: zero is definitely even!

Detailed Summary: Odd and Even Numbers

Definitions

Even Numbers: Whole numbers that can be divided by 2 with no remainder. They can be perfectly paired or grouped into sets of 2.

Odd Numbers: Whole numbers that cannot be divided by 2 without a remainder. When grouped into pairs, there is always 1 left over.

Division Test: A number is even if dividing by 2 results in no remainder; odd if there's a remainder of 1.

Last Digit Rule: A quick way to identify odd/even numbers by looking at the final digit.

Core Rules and Laws
  • Even Rule: n ÷ 2 = whole number (no remainder), where n is even
  • Odd Rule: n ÷ 2 = whole number with remainder 1, where n is odd
  • Last Digit Rule: Even numbers end in 0, 2, 4, 6, or 8; odd numbers end in 1, 3, 5, 7, or 9
  • Alternating Pattern Rule: In counting order, even and odd numbers alternate (even, odd, even, odd...)
Step-by-Step Methods
  1. Identify the Number: Look at the number you want to classify
  2. Apply Division Test: Divide the number by 2 and check for remainder
  3. Use Last Digit Method: Check if the final digit is even (0,2,4,6,8) or odd (1,3,5,7,9)
  4. Visual Pairing: Imagine grouping objects into pairs to see if one is left over
  5. Verify Result: Double-check using a different method
Examples (Simple → Advanced)
Simple Example
Number 4: 4 ÷ 2 = 2 remainder 0 → Even
Number 5: 5 ÷ 2 = 2 remainder 1 → Odd
Intermediate Example
Number 12: Ends in 2 (even digit) → Even
Number 13: Ends in 3 (odd digit) → Odd
Advanced Example
Number 246: Ends in 6 (even digit) → Even
Number 357: Ends in 7 (odd digit) → Odd
Tips, Tricks, and Common Pitfalls
  • Tip 1: Remember the rhyme: "0, 2, 4, 6, 8 - being even is really great!"
  • Tip 2: Practice with physical objects like counters or toys to visualize pairing
  • Tip 3: Notice that even and odd numbers alternate in counting order
  • Pitfall 1: Thinking 0 is odd (zero is actually even: 0 ÷ 2 = 0 remainder 0)
  • Pitfall 2: Forgetting that the pattern alternates: even, odd, even, odd...
  • Pitfall 3: Misidentifying large numbers without checking the last digit
Key Notes for Memorization
  • Even numbers: 0, 2, 4, 6, 8 - they end in these digits
  • Odd numbers: 1, 3, 5, 7, 9 - they end in these digits
  • Even numbers can be perfectly paired (no leftovers)
  • Odd numbers always have one left over when pairing
  • Remember: 0 is even (not odd) because 0 ÷ 2 = 0 remainder 0
  • For any number, only the last digit matters for odd/even classification