Я пересчитала монеты и положила сдачу в карман куртки.

Because they’re past-tense verbs agreeing with a female speaker. In Russian, past tense changes for gender/number:

• male: я пересчитал(∅), я положил(∅)
• female: я пересчитала, я положила
• plural: мы пересчитали, мы положили

So this sentence implies the speaker Я is a woman (or the narrator chooses feminine agreement).

Both are perfective: пересчитать (to count through / count up, finish counting) and положить (to put, one completed action). Perfective is used for completed, one-time actions, often in sequence: did X and then did Y.

Imperfective alternatives would suggest process/habit/background:

• Я пересчитывала монеты = I was counting the coins / I used to count coins (context-dependent)
• Я клала сдачу в карман = I was putting the change in my pocket (process/repeated action)

The prefix changes the nuance:

• считать = to count (imperfective)
• посчитать = to count (perfective, “count up” once)
• пересчитать = to recount / count through (perfective), often implying you check the amount carefully or count again to be sure.

So пересчитала монеты sounds like I counted the coins (to make sure / fully).

It’s accusative plural, but for inanimate nouns the accusative plural is the same as the nominative plural:

• nominative plural: монеты
• accusative plural (inanimate): монеты

So it’s the direct object of пересчитала.

Сдача means change (money you get back after paying). In the sentence it’s in the accusative singular because it’s the direct object of положила:

• nominative: сдача
• accusative: сдачу

They’re an aspect pair:

• класть = imperfective (putting, process/repetition)
• положить = perfective (put once, completed)

Since the sentence describes finished actions (counted and put), положила is the natural choice.

Because в + accusative indicates motion into something:

• положила в карман = put (it) into the pocket (destination)

в + prepositional indicates location:

• лежит в кармане = is lying in the pocket (location)

So в карман is correct with положила.

Куртки is genitive singular, showing possession/association: the pocket of the jacket.

• nominative: куртка
• genitive: куртки

This “noun + genitive” structure is extremely common in Russian for “X of Y.”

Yes, but they mean different things because of the case after в:

• в карман куртки = into the jacket’s pocket (motion + destination)
• в кармане куртки = in the jacket’s pocket (location)

Your sentence correctly uses в карман куртки because the action is putting into.

Russian normally doesn’t repeat the subject pronoun if it’s obvious:

• Я пересчитала … и положила … = I counted … and (I) put …

Repeating я would usually add emphasis or contrast.

Common stresses here are:

• я пересчитАла
• положИла
• монЕты
• сдАчу
• кармАн
• кУртки (from кУртка)