Length of river Narmada is about 1290 km. Its length in metres is ____.
1,290,000 m
We are given the length in kilometres: \(1290\) km.
Recall the basic fact: \(1\,\text{km} = 1000\,\text{m}\).
So to change kilometres to metres, we multiply by \(1000\).
Write the multiplication: \(1290 \times 1000\).
Multiplying by \(1000\) means adding three zeros to the number.
Therefore: \(1290 \times 1000 = 1290000\).
Add commas for reading: \(1,290,000\).
Include the unit: \(1,290,000\,\text{m}\).