Addition? But I'm doing my homework right now...*toss*We'll do subtraction too, but first you should do multiplication. Multiplication uses addition, you see. Like, 2 × 3 means "add 2 to itself 3 times."Hana and Hachi*woof woof woof woof woof*MultiplicationHuh?Mm-hmm...I'm going to teach Hachi!Hey, hey, Onee-chan, can you teach me addition?*woof woof woof woof woof woof woof woof woof woof woof woof woof woof woof**woof woof*AdditionHey, hey, Onee-chan, now that I understand addition, can you teach me subtraction next?Mom, that's amazing!All right, I'll teach you. Listen carefully. Let's say, for 1 + 1, that I have one piece of one kind of candy and one piece of another kind of candy. How many do I have all together? It's the same thing.Hachi, be quiet for a little.Oh...2 + 3 is similar...You don't need to teach Hachi. He's much smarter than you already.Hm... that's simple.I remember all of my single-digit multiplication tables! 2 × 9 is 18, 3 × 9 is 27, and 9 × 9 is 81.So this is the insurmountable wall that exists between adults and children...But when I get to 2 × 9 or 3 × 9 it gets hard...That's why humans invented the civilized convenience of the pocket calculator. They wouldn't need it in the first place if they hadn't invented multiplication, but... humans are total fools.