Here's why:

* Table fans are relatively low-power devices. They don't require the precise waveform of a pure sine wave inverter, making a modified sine wave inverter a more affordable option.

* Modified sine wave inverters are generally cheaper than pure sine wave inverters.

However, there are a few things to consider:

* Check the fan's wattage: Make sure the inverter has a higher wattage rating than the fan to avoid overloading it.

* Some fans might be sensitive to the waveform: If the fan runs erratically or makes strange noises, a pure sine wave inverter might be a better choice.

* Consider the frequency: Make sure the inverter outputs the correct frequency for your fan's operating region. Most fans work on 50Hz or 60Hz.

In general, a modified sine wave inverter will work well for most table fans. However, if you experience any issues, it's worth trying a pure sine wave inverter.