Question 1
Prove that the sum of two consecutive odd numbers is divisible by 4.
Let's use algebra to represent any two consecutive odd numbers.
Step 1 — Representing the numbers
We need to pick any odd number. Let's use a variable for this. An odd number can be written as . Here, is any whole number. The next consecutive odd number is more than the first. So, we add 2 to our first number.

Step 2 — Finding their sum
Now, let's add these two consecutive odd numbers. We will sum the first odd number and the second odd number.
We can see that 4 is a common factor here. Let's factor out 4 from the sum.
Since is a whole number, is also a whole number. This means the sum is 4 multiplied by a whole number. Any number that can be written as 4 times a whole number is divisible by 4.
Answer
The sum of two consecutive odd numbers is divisible by 4.
More questions in A1.3
Prove that the sum of two consecutive odd numbers is divisible by 4.
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