Token usage and cost tracking in Agentic AI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the token counter variable.

Agentic AI

token_count = [1]

Drag options to blanks, or click blank then click option'

A0

BNone

C1

D''

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing token_count to None or an empty string instead of zero.

We start counting tokens from zero, so initializing token_count to 0 is correct.

2fill in blank

medium

Complete the code to add the number of tokens used in the current step to the total count.

Agentic AI

token_count [1]= tokens_used

Drag options to blanks, or click blank then click option'

A+

B*

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

We add the tokens used in the current step to the total token_count using '+='.

3fill in blank

hard

Fix the error in the code to calculate the cost based on tokens used and price per token.

Agentic AI

cost = tokens_used [1] price_per_token

Drag options to blanks, or click blank then click option'

A+

B-

C/

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or division instead of multiplication.

Cost is calculated by multiplying tokens used by price per token, so '*' is correct.

4fill in blank

hard

Fill both blanks to create a dictionary that tracks tokens and cost for each step.

Agentic AI

usage = {'tokens': [1], 'cost': [2]

Drag options to blanks, or click blank then click option'

Atokens_used

Btotal_cost

Ccost

Dtoken_count

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing total_cost with cost for the current step.

The 'tokens' key should hold tokens_used, and 'cost' should hold the calculated cost.

5fill in blank

hard

Fill all three blanks to update total tokens, calculate cost, and store usage info.

Agentic AI

token_count [1]= tokens_used
cost = tokens_used [2] price_per_token
usage = {'tokens': tokens_used, 'cost': [3]

Drag options to blanks, or click blank then click option'

A+

B*

Ccost

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong operators or storing wrong values in usage.

We add tokens_used to token_count, multiply tokens_used by price_per_token for cost, and store cost in usage.

Practice

1. What is a token in the context of AI language models?

easy

A. A programming language used for AI

B. A type of AI model architecture

C. A small piece of text like a word or part of a word

D. A hardware component for AI processing

Solution

1. Step 1: Understand the definition of a token

   A token is a small piece of text that AI models use to understand language. It can be a word or part of a word.

2. Step 2: Differentiate tokens from other AI terms

   Tokens are not models, programming languages, or hardware. They are units of text input.

3. Final Answer:

   A small piece of text like a word or part of a word -> Option C

4. Quick Check:

   Token = small text piece [OK]

Hint: Tokens are text pieces, not models or hardware [OK]

Common Mistakes:

• Confusing tokens with AI models
• Thinking tokens are programming languages
• Assuming tokens are hardware parts

2. Which of the following is the correct way to track token usage in a Python script using an AI API?

easy

A. tokens_used = response['total_tokens']

B. tokens_used = response['usage']['total_tokens']

C. tokens_used = response['usage']['tokens']

D. tokens_used = response['token_count']

Solution

1. Step 1: Identify the correct key for token usage in API response

   Most AI APIs return token usage under response['usage']['total_tokens'].

2. Step 2: Compare options with common API response structure

   Only tokens_used = response['usage']['total_tokens'] matches the standard nested key for total tokens used.

3. Final Answer:

   tokens_used = response['usage']['total_tokens'] -> Option B

4. Quick Check:

   Correct key path = response['usage']['total_tokens'] [OK]

Hint: Look for nested 'usage' then 'total_tokens' key [OK]

Common Mistakes:

• Using wrong key names like 'token_count'
• Missing nested 'usage' dictionary
• Assuming flat keys for token counts

3. Given the following code snippet, what will be printed?

response = {'usage': {'prompt_tokens': 50, 'completion_tokens': 30, 'total_tokens': 80}}
print(response['usage']['total_tokens'])

medium

A. 80

B. 30

C. 50

D. Error

Solution

1. Step 1: Access the 'total_tokens' key in the nested dictionary

   The code accesses response['usage']['total_tokens'], which is 80.

2. Step 2: Confirm the print output

   Printing this value outputs 80 without error.

3. Final Answer:

   80 -> Option A

4. Quick Check:

   response['usage']['total_tokens'] = 80 [OK]

Hint: Check nested dictionary keys carefully [OK]

Common Mistakes:

• Confusing prompt_tokens with total_tokens
• Mixing completion_tokens with total_tokens
• Assuming code causes error

4. You wrote this code to track token usage but get a KeyError:

tokens = response['usage']['token_total']
print(tokens)

What is the likely cause?

medium

A. The 'usage' key is missing in the response

B. The response variable is not defined

C. The print statement syntax is incorrect

D. The key 'token_total' does not exist in the response dictionary

Solution

1. Step 1: Check the key names in the response dictionary

   The correct key is 'total_tokens', not 'token_total'.

2. Step 2: Understand KeyError cause

   Using a wrong key name causes KeyError because that key does not exist.

3. Final Answer:

   The key 'token_total' does not exist in the response dictionary -> Option D

4. Quick Check:

   Wrong key name causes KeyError [OK]

Hint: Verify exact key names in API response [OK]

Common Mistakes:

• Assuming similar key names exist
• Ignoring case sensitivity in keys
• Thinking print syntax causes error

5. You want to estimate the cost of an AI request. The model charges $0.002 per 1000 tokens. If your request uses 2500 tokens, what is the total cost?

hard

A. $0.005

B. $0.0025

C. $0.05

D. $0.0005

Solution

1. Step 1: Calculate cost per token

   Cost per token = $0.002 / 1000 = $0.000002 per token.

2. Step 2: Multiply by number of tokens used

   Total cost = 2500 tokens * $0.000002 = $0.005.

3. Final Answer:

   $0.005 -> Option A

4. Quick Check:

   2500 tokens x $0.002/1000 = $0.005 [OK]

Hint: Multiply tokens by cost per token (divide by 1000 first) [OK]

Common Mistakes:

• Multiplying by 0.002 directly without dividing by 1000
• Using wrong token count
• Confusing decimals in cost calculation