Question
Multiply:
This is a Class 6 NCERT favourite — simple to do, but students mess up the decimal placement more often than you’d expect.
Solution — Step by Step
Treat as and as . Multiply them normally:
We do this first because decimal multiplication is really just whole number multiplication — we’ll handle the decimal point separately.
has 1 decimal place (one digit after the point).
has 1 decimal place.
Total decimal places = .
We have from Step 1. We need to put 2 decimal places in it.
Count 2 digits from the right of : .
Why This Works
When we write , we mean . Similarly, means .
So the multiplication is actually:
The denominator becomes because we multiplied two tenths together — which gives hundredths. That’s exactly why the answer has 2 decimal places when each factor had 1.
This is the logic behind the “count and place” rule. You’re not memorising a trick — you’re doing fraction multiplication in disguise.
Alternative Method — Using Fractions Directly
Convert each decimal to a fraction, multiply, then convert back.
This method is slower for calculation, but it’s worth doing once or twice in your notebook — it makes the “why” very clear before you rely on the shortcut.
Common Mistake
Writing the answer as 1.2 instead of 0.12.
Students multiply correctly, then place only 1 decimal point (getting ) instead of 2. Always count the total decimal places in both numbers — not just one of them. Here, both and contribute one place each, so the answer needs two places total.
Quick self-check: must be less than . So if your answer is , that’s already bigger than one of the factors — something’s off. Use this sense-check in exams when you’re unsure.