To convert the maximum size that the TV stand can hold from millimeters to inches, you can use the conversion factor where 1 inch is equal to 25.4 millimeters.
The maximum size in millimeters is 400 mm x 400 mm.
To convert 400 mm to inches:
\[ \text{Size in inches} = \frac{\text{Size in mm}}{25.4} \]
Calculating for 400 mm:
\[ \text{Size in inches} = \frac{400}{25.4} \approx 15.748 \]
Since you’re looking for a full solid number, you would typically round this down to the nearest whole number, which gives you 15 inches.
Thus, the maximum size the TV can hold, expressed in whole inches, is approximately 15 inches.