🐍 Python from scratch · Session 2

Variables: boxes that remember: practice sheet

Name ____________________Date __________Score ____ / 28

Part 1: Making a variable

Remember: A variable is a name that holds a value, like a labelled box: age = 11. In Python = means "put the value on the right into the box on the left".

1. Warm-up The variable name is already made. Print Hello, followed by the name (use a comma).
```
name = "Zara"
```
2. Warm-up Make a = 6 and b = 7 and print their product.
3. Core price = 40 and qty = 3. Print Cost: and the cost.
```
price = 40
qty = 3
```
4. Stretch 🔥 side = 5. Print two lines: Area: … and Perimeter: … of a square with that side.
```
side = 5
```

Part 2: Changing a variable

Remember: Giving a variable a new value replaces the old one. score = score + 10 means: take what is in score, add 10, put it back.

5. Warm-up score starts at 0. Add 5 three times using += and print score.
```
score = 0
```
6. Core money = 100. Spend 35, earn 20, then double what is left. Print money.
```
money = 100
```
7. Stretch 🔥 Swap the values of a and b, then print a and b on one line. (Hint: a third box.)
```
a = 1
b = 2
```

Part 3: Maths operators

Remember: // divides and drops the remainder, % gives only the remainder, ** is "to the power of". / always gives a decimal answer.

8. Warm-up Print 17 // 5 on one line and 17 % 5 on the next.
9. Core sweets = 47 are shared equally by kids = 6. Print Each: … and Left: ….
```
sweets = 47
kids = 6
```
10. Core n = 2468. Print its last digit using %.
```
n = 2468
```
11. Stretch 🔥 n = 4729 (always 4 digits). Print the sum of its digits using // and %.
```
n = 4729
```
12. Stretch 🔥 days = 1000. Print how many whole years (365 days) and days that is, like: 2 years 270 days
```
days = 1000
```

Part 4: Neat printing with f-strings

Remember: An f-string has f before the quote; variables go inside curly brackets and are filled in: f"{name} is {age}".

13. Warm-up Print exactly: Ravi is 12 years old. using an f-string and the variables.
```
name = "Ravi"
age = 12
```
14. Core Print: A 8 by 5 rectangle has area 40. (all three numbers from the variables)
```
l = 8
w = 5
```
15. Stretch 🔥 price = 250 and off = 20 (percent). Print Sale price: and the new price, worked out inside the f-string.
```
price = 250
off = 20
```

Activity 1: The shop bill

16. Work out a bill for 2 pencils, 3 notebooks and 1 eraser, a discount of one tenth of the total (whole rupees), and what is left to pay. Print exactly three lines: Total: …, Discount: … and To pay: …. It must still be right if a price changes.
1. Work out total = 2 pencils + 3 notebooks + 1 eraser, using the price variables.
2. Work out discount = total // 10.
3. Work out pay = total - discount.
4. Print the three lines with f-strings.
```
pencil = 12
notebook = 45
eraser = 8

# Step 1: total
total = 0

# Step 2: discount (one tenth, whole rupees)

# Step 3: pay

# Step 4: print Total:, Discount:, To pay:
```

Activity 2: Time converter

17. seconds = 3725. Print one line: 1 hours 2 minutes 5 seconds. It must work for any number of seconds.
1. hours = seconds // 3600 (there are 3600 seconds in an hour).
2. rest = seconds % 3600 (seconds left after the whole hours).
3. minutes = rest // 60 and secs = rest % 60.
4. Print the line with an f-string.
```
seconds = 3725

# Step 1: whole hours

# Step 2: what is left

# Step 3: minutes and seconds

# Step 4: print
```

Activity 3: Report card

18. Three test marks out of 100 are given. Print exactly: Total: …, Average: … and Percent: … (the percentage of 300). It must work for any marks.
1. total = m1 + m2 + m3.
2. average = total / 3.
3. percent = total / 300 * 100.
4. Print three lines with f-strings.
```
m1 = 78
m2 = 92
m3 = 85

# Step 1

# Step 2

# Step 3

# Step 4
```

Predict the output

Work it out on paper first, then type it into the lesson page to check.

19. What does this print?
```
x = 5
x = x + 2
print(x)
```
20. What does this print?
```
print(7 // 2)
```
21. What does this print?
```
print(23 % 5)
```
22. What does this print?
```
print(2 ** 3)
```
23. What does this print?
```
name = "Sam"
print(f"Hi {name}")
```
24. What does this print?
```
a = 3
b = a
a = 10
print(b)
```
25. What does this print?
```
n = 345
print(n // 10 % 10)
```

Homework

26. Warm-up length = 12 and width = 5: print the area and the perimeter of the rectangle on two lines.
```
length = 12
width = 5
```
27. Core seconds = 500. Print like: 8 minutes 20 seconds
```
seconds = 500
```
28. Stretch 🔥 n = 357 (3 digits). Print the number with its digits reversed (753), worked out with // and %.
```
n = 357
```

Answer key

```
name = "Zara"
print("Hello,", name)
```
```
a = 6
b = 7
print(a * b)
```

price = 40
qty = 3
print("Cost:", price * qty)

side = 5
print("Area:", side * side)
print("Perimeter:", 4 * side)

score = 0
score += 5
score += 5
score += 5
print(score)

money = 100
money -= 35
money += 20
money *= 2
print(money)

a = 1
b = 2
temp = a
a = b
b = temp
print(a, b)

```
print(17 // 5)
print(17 % 5)
```

sweets = 47
kids = 6
print("Each:", sweets // kids)
print("Left:", sweets % kids)

```
n = 2468
print(n % 10)
```

n = 4729
a = n // 1000
b = n // 100 % 10
c = n // 10 % 10
d = n % 10
print(a + b + c + d)

days = 1000
print(days // 365, "years", days % 365, "days")

name = "Ravi"
age = 12
print(f"{name} is {age} years old.")

l = 8
w = 5
print(f"A {l} by {w} rectangle has area {l * w}.")

price = 250
off = 20
print(f"Sale price: {price * (100 - off) / 100}")

pencil = 12
notebook = 45
eraser = 8
total = 2 * pencil + 3 * notebook + eraser
discount = total // 10
pay = total - discount
print(f"Total: {total}")
print(f"Discount: {discount}")
print(f"To pay: {pay}")

seconds = 3725
hours = seconds // 3600
rest = seconds % 3600
minutes = rest // 60
secs = rest % 60
print(f"{hours} hours {minutes} minutes {secs} seconds")

m1 = 78
m2 = 92
m3 = 85
total = m1 + m2 + m3
average = total / 3
percent = total / 300 * 100
print(f"Total: {total}")
print(f"Average: {average}")
print(f"Percent: {percent}")

7
3
3
8
Hi Sam
3
4

length = 12
width = 5
print(length * width)
print(2 * (length + width))

seconds = 500
print(f"{seconds // 60} minutes {seconds % 60} seconds")

n = 357
print(n % 10 * 100 + n // 10 % 10 * 10 + n // 100)