Question

# How many centimetres make a kilometre?

Hint: Use the conversion formulas $1km=1000m$ and $1m=100cm$ for converting one unit system to another to get the number of centimetres in one kilometre. As $1m=100cm$, convert $1000m$ into centimetres by multiplying it by $100$.
We know that $1km=1000m$. We now have to convert metres into centimetres. We know that $1m=100cm$.
Thus, to convert $1000m$ into centimetres, we will multiply it by $100$.
So, we have $1000m=1000\times 100cm={{10}^{5}}cm$.
Thus, we get $1km=1000m={{10}^{5}}cm$.