I will reply once.
Using a calculator, to help a child learn math teaches nothing. when the test comes they no longer have access to the calculator.
It helps them not at all.
If you never learn strategies to multiply and were given a calculator you will not know how to multiply when the time comes.
Calculators come after you know the basics and are used to increase efficiency. They are not designed to replace the human capacity to do multiplication.
Which in this scenario is exactly what it would do.