Numbers Everywhere! From Phones to Cars

Tiny math, giant world

Now that we've covered Coding with Colors - Intro to Python and Java, you have seen that code can store labels, lists, and clues.

In this lesson, we zoom out: phones, cars, watches, games, maps, and robots are all quietly using numbers.

A data scientist asks:

• What number was measured?
• What does it describe?
• What unit does it use?
• How can a computer use it to help?

Think of each number as a tiny whisper from the real world.

Your phone is a number collector

A phone does not only show pictures and apps. It also keeps many number clues.

Examples:

Phone clue Example number Meaning Battery 72 72% full Signal bars 3 connection strength Steps today 2840 walking count Brightness 60 screen light level Storage used 48 gigabytes used

From earlier lessons, you already know these can live in a dictionary because each number has a label.

```python
phone = {
    'battery_percent': 72,
    'signal_bars': 3,
    'steps_today': 2840,
    'brightness_percent': 60,
    'storage_used_gb': 48
}

print('Phone snapshot:')
for clue, number in phone.items():
    print(clue, '->', number)

print('Battery left:', phone['battery_percent'], '%')
print('Steps today:', phone['steps_today'])
```

A phone fitness app wants to learn whether you walked more today than yesterday.

Which item is the most useful number data for that question?

A car is like a rolling data machine

A car has small helpers called sensors. A sensor notices something in the world and turns it into a number.

Examples:

• Speed sensor: 50 km/h
• Fuel or battery sensor: 35%
• Temperature sensor: 24°C
• Tire pressure sensor: 32 psi
• Distance sensor: 2 meters from object

The car computer does not feel scared, hot, or fast like a person. It reads numbers, then follows rules and algorithms.

A car thermometer writes down 22°C, then 23°C, then 23°C again.

Each written sensor number is called a sensor ____.

A number needs its name tag

The same number can mean very different things.

30 by itself is lonely.

But with a unit, it becomes clear:

• 30 minutes = time
• 30°C = temperature
• 30 km/h = speed
• 30 dollars = money
• 30 steps = walking count

In data science and machine learning, a number without context can trick us. Good data keeps the label and the unit close to the number.

Tiny rule: number + label + unit = useful measurement.

True or false?

The number 100 always means the same thing in every dataset, even if we do not know its label or unit.

A trip becomes rows of data

Imagine a car writes one row every minute.

Each row is a small snapshot:

• minute number
• speed
• battery percent
• outside temperature

This is like the datasets you will see in data science: many rows, each with useful number clues.

```python
trip = [
    {'minute': 1, 'speed_kmh': 0,  'battery_percent': 80, 'temp_c': 21},
    {'minute': 2, 'speed_kmh': 30, 'battery_percent': 79, 'temp_c': 21},
    {'minute': 3, 'speed_kmh': 45, 'battery_percent': 78, 'temp_c': 22},
    {'minute': 4, 'speed_kmh': 40, 'battery_percent': 77, 'temp_c': 22}
]

speeds = [row['speed_kmh'] for row in trip]
batteries = [row['battery_percent'] for row in trip]

typical_speed = sum(speeds) / len(speeds)
lowest_battery = min(batteries)

print('Speeds:', speeds)
print('Typical speed:', typical_speed, 'km/h')
print('Lowest battery:', lowest_battery, '%')
```

Computers use numbers to choose

A useful computer program often follows this path:

real world -> numbers -> code -> helpful action

Example: a phone or car can warn us when a number crosses a limit.

This is not magic. It is the same idea from Fun with Algorithms: Cooking Recipes and Using Computers to Solve Problems: read input, process it, then give output.

```python
battery_percent = 18
distance_to_charger_km = 6

print('Battery:', battery_percent, '%')
print('Distance to charger:', distance_to_charger_km, 'km')

if battery_percent < 20 and distance_to_charger_km > 5:
    print('Action: Please charge soon!')
elif battery_percent < 20:
    print('Action: Battery is low, but charger is nearby.')
else:
    print('Action: Battery looks okay.')
```

What you learned

Numbers are everywhere, but useful data is more than just digits.

A good data thinker asks:

1. What is being measured? Battery, speed, steps, temperature?
2. What is the label? What does the number describe?
3. What is the unit? Percent, km/h, °C, meters?
4. What can code do with it? Sort it, average it, compare it, warn us, or help us decide.

Phones and cars are friendly examples of a bigger idea: data science, AI, and machine learning begin by turning the world into well-labeled numbers.

Next, we will celebrate how all these math and science ideas connect.