Unit Price Calculator - Problem

You are shopping at a grocery store and need to calculate the unit price of an item to compare value between different products.

Given the total price of an item and its quantity, calculate the unit price (price per single unit) rounded to 2 decimal places.

Formula: unit_price = total_price / quantity

Input: Two numbers - total price and quantity

Output: Unit price rounded to 2 decimal places

Input & Output

Example 1 — Basic Calculation

$ Input: totalPrice = 12.50, quantity = 5

› Output: 2.50

💡 Note: Unit price = 12.50 ÷ 5 = 2.50 per item

Example 2 — Rounding Required

$ Input: totalPrice = 10.00, quantity = 3

› Output: 3.33

💡 Note: Unit price = 10.00 ÷ 3 = 3.333... rounds to 3.33

Example 3 — Exact Division

$ Input: totalPrice = 8.00, quantity = 4

› Output: 2.00

💡 Note: Unit price = 8.00 ÷ 4 = 2.00 exactly

Constraints

0.01 ≤ totalPrice ≤ 1000.00
1 ≤ quantity ≤ 1000
Result rounded to exactly 2 decimal places

Visualization

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Asked in

a Amazon 15 W Walmart 12

The key insight is to perform simple division and handle floating-point precision correctly. The optimal approach divides total price by quantity and uses precision-aware rounding (multiply by 100, round, divide by 100) to ensure exactly 2 decimal places. Time: O(1), Space: O(1)

Common Approaches

✓ Direct Division

⏱️ Time: O(1) Space: O(1)

This straightforward approach performs the division operation and uses built-in rounding functions to format the result to 2 decimal places. No optimization needed since it's a single mathematical operation.

Precision-Aware Division

⏱️ Time: O(1) Space: O(1)

To avoid floating point precision issues, multiply the result by 100, round to nearest integer, then divide by 100. This ensures accurate rounding to exactly 2 decimal places.

Direct Division — Algorithm Steps

Divide total price by quantity
Round result to 2 decimal places

Visualization

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Step-by-Step Walkthrough

Input Values

Get total price and quantity

Divide

Calculate totalPrice ÷ quantity

Round

Round to 2 decimal places

Code -

solution.c — C

#include <stdio.h>
#include <math.h>

double solution(double totalPrice, int quantity) {
    double unitPrice = totalPrice / quantity;
    return round(unitPrice * 100.0) / 100.0;
}

int main() {
    double totalPrice;
    int quantity;
    
    scanf("%lf", &totalPrice);
    scanf("%d", &quantity);
    
    double result = solution(totalPrice, quantity);
    printf("%.2f\n", result);
    
    return 0;
}

Time & Space Complexity

Time Complexity

⏱️

O(1)

Single division and rounding operation

✓ Linear Growth

Space Complexity

O(1)

Only storing the result variable

✓ Linear Space

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Medium Frequency

~5 min Avg. Time

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Unit Price Calculator - Problem

Input & Output

Constraints

Visualization

Related Problems

Common Approaches

Direct Division — Algorithm Steps

Visualization

Code -

Time & Space Complexity

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