Now take a loop around the lip of this coffee mug. You can contract it to a point by bringing it all over the lip of the mug, then inside, along the outer walls, and then finally down to the bottom of the mug.
Nope, donut hole is in the way.
Now take a loop around the lip of this coffee mug. You can contract it to a point by bringing it all over the lip of the mug, then inside, along the outer walls, and then finally down to the bottom of the mug.
Nope, donut hole is in the way.
I’m guessing they did the 4 x 3, noticed they had to carry, accidentally wrote the carry in the wrong column, then immediately went and added that carry to their leftover 2, thus only counting 3 in total.