My bathroom is 4 square meters and my kitchen is 8 square meters. How many wall tiles do I need to buy?

It is suggested not to use big bricks in the kitchen and bathroom, which is not only costly, but also unsightly, so don't make people laugh. Generally, there are 3 * 3 and 3 * 26, etc. The bathroom floor tiles need to be about 4.5 square meters, the wall tiles need to be about 2 square meters, the kitchen floor tiles need to be 8.5~9 square meters, and the wall tiles need to be 31 square feet. If it is four sliding doors, it can be less.