Diced Tomatoes

If I set a tomato on the counter and passed a knife half way through it, would I be adding to or subtracting from the tomato? To think that I did add to the tomato or subtract from it would ascribe some strange characteristics to the knife.
Since a boundary is not a difference, it can neither add to nor subtract from the thing that it is applied to.
Yet every day, and every day for thousands of years people have been taught that the knife has subtracted from the tomato.
Since the addition or subtraction of a boundary does not change the material that becomes bounded, no change in the material can ever take place, yet just the opposite is taught and has been taught for a very long time. How?
What is 10 divided by 2?
5 you say? I say that has to be magic. Applying a boundary, divisor, it is not possible that 10 divided by 2 equals 5.
10 divided by 2 = 5 x 2.
And again, and I am going to address one of Bertrand Russell’s confusions he could not figure out.
Does A = A? Yes, of course you say.
Then I say, how is it then possible that 5 x 5 = 25?
It is not. It is no more rational than to say that 10 divided by 2 equals 5.
5 things in 5 groups equals 25 things in one group.
10 things divided into two equal groups equals 5 things in 2 groups.

How is it possible to teach about form and material if the lessons we give children keep contradicting the principles of logic?