Implemented getReminder() and calculateTotalPrice()

[ddryzhov]

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[Copilot]

Pull request overview

Implements the previously stubbed Kotlin utility functions for computing a total price with a default unit price and for transforming a numeric string into a remainder value.

Changes:

• Implement calculateTotalPrice() to apply a default unit price when pricePerProduct is null and multiply by count.
• Implement getReminder() to parse an optional numeric string and compute (n * 3 + 10) % 11.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/main/kotlin/mate/academy/TotalPrice.kt	Adds default-price handling and computes total price.
src/main/kotlin/mate/academy/NumberTransformation.kt	Adds parsing and transformation logic for the remainder calculation.

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[Copilot]

The arithmetic (number * 3 + 10) is performed in Int and can overflow for large (but still valid) Int inputs, producing an incorrect remainder. Consider doing the computation in Long (or using exact math) before applying % 11 and returning the Int result.

Suggested change

	return numberStr?.toIntOrNull()?.let { number -> (number * 3 + 10) % 11 }
	return numberStr?.toIntOrNull()?.let { number -> ((number.toLong() * 3 + 10) % 11).toInt() }