Understand the formula and extract data.

The formula for population density is given as:

$$\text{Population Density} = \frac{\text{Total Population of Country}}{\text{Total area of Country}}$$

We will use the data from the provided table for each country.

From the table, Japan's population is 127,000,000 and its land area is 378,000 km$^2$.

$$\text{Population Density (Japan)} = \frac{127,000,000}{378,000} \approx 335.98 \text{ people/km}^2$$

From the table, India's population is 1,150,000,000 and its land area is 3,170,000 km$^2$.

$$\text{Population Density (India)} = \frac{1,150,000,000}{3,170,000} \approx 362.78 \text{ people/km}^2$$

From the table, Russia's population is 141,000,000 and its land area is 17,100,000 km$^2$.

$$\text{Population Density (Russia)} = \frac{141,000,000}{17,100,000} \approx 8.25 \text{ people/km}^2$$

From the table, Indonesia's population is 238,000,000 and its land area is 190,000 km$^2$.

$$\text{Population Density (Indonesia)} = \frac{238,000,000}{190,000} \approx 1252.63 \text{ people/km}^2$$

From the table, Nigeria's population is 138,000,000 and its land area is 923,768 km$^2$.

$$\text{Population Density (Nigeria)} = \frac{138,000,000}{923,768} \approx 149.39 \text{ people/km}^2$$

Here are the results in the requested table format:

COUNTRY	POPULATION DENSITY (people/km$^2$)
Japan	$\boxed{\text{335.98}}$
India	$\boxed{\text{362.78}}$
Russia	$\boxed{\text{8.25}}$
Indonesia	$\boxed{\text{1252.63}}$
Nigeria	$\boxed{\text{149.39}}$