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### Course: Math for fun and glory>Unit 5

Lesson 4: Arithmetic warmups

# Exponentiation warmup

introduction to exponents and exponential growth. Created by Sal Khan.

## Want to join the conversation?

• at ,brit says that the last square is the 63rd . but arent there 64 squares on a chess board?
• he said 63 steps. It does take 63 steps to move from start to 64
• Why did i laugh at the part of when he collects the grains of rice over night?
• it is just the fact that people don't generally do that every night.
• what if you doubled the grain of rice then what would you do?
• Is he done counting that out yet in rice?
• Are exponents the same as indices or is it completely different ?
• Interesting, I've never heard them called indecies.
(1 vote)
• Is there a name for that tree that they made?
• You can call a tree in which each branch splits into two at each level can be called a binary tree (but strictly speaking, a binary tree can have branches that don't split at each level).
• if a tree that splits twice is a binary tree, what is a tree that splits four times?
• Why when I think of a mount Everest sized mound of rice, it feels impossible?
• Well, 92,233,720,000,000,000,000 grains of rice is pretty large. Annual consumption of rice globally is about 4,777,700,000,000,000 grains of rice. So that would be as much rice as would feed the world for over 19,000 years!

wow.................
• At , doesn't it look like that stick figure is a leaping deer?
• Can you do more videos like this?
• these videos are amazing will you guys make more?
(1 vote)
• Ok so the question in the video asks how much grain of rice is in the last square.

If the question was: "I give you one rice for the first day, then two in the second and i keep doubling, how many grains of rice would you have by the 5th day?"

Would it be correct to say its 2^5-1?

1+2+4+8+16 = 31?.