Tan + adjective/adverb = SO + adjective/adverb:
The fur coat is so expensive.
Question number four is so difficult.
These shoes are so big.
Tanto "a secas" = SO MUCH:
I love her so much.
Tanto + uncountable noun = SO MUCH + u. noun
He eats so much fruit / cereal.
She drinks so much milk.
She drinks so much milk.
There was so much traffic.
He gave us to much homework.
Some politicians earn so much money.
Tantos + countable noun = SO MANY + c. noun
She invited so many people.
Do you think there are so many children in this class?
Don't eat so many sweets!
These forms are very often followed by a clause (formando así una frase subordinada consecutiva: tan largo que..., tan emocionante que... tanta gente que...trabaja tanto que...). Before the clause you may find the word that, but it is often dropped (antes de la subordinada puede aparecer la conjunción that = que, pero en lenguaje coloquial a menudo se omite):
There were so many people (that) we had to get more chairs.
The film was so boring (that) everyone fell asleep.
I ate so much cake (that) I wasn't hungry for the rest of the day.
Tantos + countable noun = SO MANY + c. noun
She invited so many people.
Do you think there are so many children in this class?
Don't eat so many sweets!
These forms are very often followed by a clause (formando así una frase subordinada consecutiva: tan largo que..., tan emocionante que... tanta gente que...trabaja tanto que...). Before the clause you may find the word that, but it is often dropped (antes de la subordinada puede aparecer la conjunción that = que, pero en lenguaje coloquial a menudo se omite):
There were so many people (that) we had to get more chairs.
The film was so boring (that) everyone fell asleep.
I ate so much cake (that) I wasn't hungry for the rest of the day.
When so, so much and so many are not followed by anything, the sentence is more like an exclamation, and the meaning of these words is similar to muy or mucho.
There was so much traffic! (¡Había un tráfico...!)
There was so much traffic! (¡Había un tráfico...!)