Why Does Shark Tank Lie About Valuation? (2016)
medium.com
medium.com
Then after a bit of Googling, I found that indeed they value them incorrectly. Most likely so as not to confuse viewers.
If the investment required is 100k for 10%, the shark would say "you value your company at $1m". Not true though. That's the value of the company after the invested $100k becomes an asset of the company.
Ergo, before the investment, the company is valued at $900k.