Writing prime factorisation without index notation
"The Index Omission"
The Mistake in Action
Write 72 as a product of prime factors.
Wrong: $72 = 2 \times 2 \times 2 \times 3 \times 3$
Why It Happens
Students correctly find all the prime factors but don't use index notation when the question requires it.
The Fix
When asked for a product of prime factors, use index notation unless told otherwise.
$$72 = 2 \times 2 \times 2 \times 3 \times 3 = 2^3 \times 3^2$$
Index notation is:
- Required in most exam questions
- Neater and clearer
- Essential for finding HCF and LCM efficiently
Always check: "Does my answer use powers?"
Spot the Mistake
Can you identify where this student went wrong?
Write 72 as a product of prime factors
$72 = 2 \times 2 \times 2 \times 3 \times 3$
Click on the line that contains the error.
Related Topics
Learn more about the underlying maths: