We're talking about a distance in astronomy, so let's associate this distance with the

**Theory of relativity**. The most famous equation in special relativity is E = mc², let's remember the

**Square**of this formula. Now let's perform some mnemonic magic.

- Perform the
**mnemonic count system**on the**Theory of relativity**: count the letters in each word and keep the last digit. Theory: 6; of: 2; relativity: (1)0 -->**620** **620² = 384.400**

It's easy, isn't it? You'll never forget that number again.

(Count("Theory of relativity"))^2 = 384.400