Tony's calculator correctly shows 3.4 x 0.5=1.7. explain why the number of decimal places in the product is not the same as the number of decimal places in the two factors.

The given product is

This results was showed by the calculator, which doesn't shows the two decimal numbers that it should have.

The reason why the calculator only shows one decimal number, it's because the second decimal number is zero, and it would be the same if we express or , that zero doesn't change the value that the number represents.

However, if we solve without calculator, we would have , because the multiplication rule states that we should add to the result as many decimal number have both factor of the multiplication, which in this case they have two.