How to make a calculation when instantiating an object?

Question

Hello, I would like to know how do for a property of an object receive a value from one against among other properties, for example

objeto = {
 valor1: 10,
 valor2: 2,
 valor3: valor1 * valor2 ????
}

I am trying to do this in typescript, but I get an error saying:

'cannot find name valor1'.

Thanks