Я сохранил квитанцию в папке, чтобы потом проверить сумму.

I kept the bill in the folder so that I could check the amount later.

Breakdown of Я сохранил квитанцию в папке, чтобы потом проверить сумму.

• я: I
• в: in
• проверить: to check
• сохранить: to keep
• папка: the folder
• сумма: the amount
• квитанция: the bill
• чтобы: so that / in order to
• потом: then/later

Questions & Answers about Я сохранил квитанцию в папке, чтобы потом проверить сумму.

Why is сохранил in the past tense, and what does it tell me about the subject?

Сохранил is past tense, perfective aspect, masculine singular.
In Russian past tense, the verb agrees with the subject in gender and number:

• я сохранил = I (male speaker) saved/kept
• If the speaker is female: я сохранила
• Plural: мы сохранили

So сохранил signals the speaker is male (or the subject is a masculine noun), and the action is viewed as completed.

What’s the difference between сохранить and сохранять?

They’re an aspect pair:

• сохранить (perfective) = to save/keep (as a completed result), “I kept it (and it’s kept now).”
• сохранять (imperfective) = to be saving/keeping regularly or as a process, or a repeated habit.

In this sentence, сохранил fits because it’s a single completed action: you put the receipt somewhere and now it’s saved.

Why is квитанцию in that form? What case is it?

квитанцию is accusative singular of квитанция (feminine). It’s the direct object of сохранил (what you saved/kept).
Dictionary form: квитанция → accusative: квитанцию.

What does квитанция mean exactly? Is it always “receipt”?

Квитанция is a “receipt” in the sense of a proof-of-payment or a payment slip (often for bills, services, fees).
For a store receipt, Russians also commonly use чек. In many contexts:

• чек = cash register receipt
• квитанция = payment receipt/slip (often more “official”)

Why is it в папке and not в папку?

Because в changes meaning depending on the case:

• в + accusative (в папку) = motion into (“into the folder”)
• в + prepositional (в папке) = location (“in the folder”)

Here the idea is where the receipt is stored/kept (location/result), so в папке is used.

Could I also say Я положил квитанцию в папку...? How is that different?

Yes, and the meaning shifts slightly:

• Я сохранил квитанцию в папке... focuses on “keeping/saving” it (so it won’t be lost).
• Я положил квитанцию в папку... focuses on the physical action of putting it into the folder.

With положил, you’d normally use в папку (accusative) because it’s motion into.

Why is there a comma before чтобы?

Because чтобы потом проверить сумму is a purpose clause (a subordinate clause of purpose). Russian typically separates the main clause and the purpose clause with a comma:

• Я сохранил квитанцию в папке, чтобы...

What does чтобы mean here, and is it different from потому что?

Here чтобы introduces purpose: “in order to / so that.”
It’s not a reason/cause.

• чтобы = purpose (goal)
• потому что = reason (“because”)

So: you kept the receipt in order to check the amount later.

Why is the verb after чтобы in the infinitive (проверить)?

When the subject is the same in both parts (here, я does both actions), Russian often uses:

• чтобы + infinitive: чтобы потом проверить

If the subject changes, you typically get a finite verb (often past tense) after чтобы, e.g. “so that he could…” would be expressed differently.

Why is it проверить (perfective) and not проверять?

проверить (perfective) implies a single complete check (“check it once and confirm”).
проверять (imperfective) would suggest an ongoing/repeated process (“to be checking / to check regularly”).

Since the idea is one later verification of the amount, проверить fits well.

Why is сумму in the accusative?

Because it’s the direct object of проверить: you “check what?” → сумму (accusative singular of сумма, feminine).
Dictionary form: сумма → accusative: сумму.

What does потом do in the sentence, and where can it go?

потом means “later / afterwards.” It sets the time for the purpose action (checking).
Common placements include:

• ..., чтобы потом проверить сумму. (very natural)
• ..., чтобы проверить сумму потом. (also possible; slightly more emphasis on “later” at the end)

Both are correct; word order mainly changes emphasis.