Values and print

A program is a list of instructions. Python reads them top to bottom and does each one. The most useful instruction at the start is print, which shows a value on the screen.

print("Welcome to the shop")
print(42)

Press Run. Two lines appear, one per print. The code boxes on this site can be edited, so change the text between the quotes and run again.

Two kinds of value

"Welcome to the shop" is text. In Python, text is called a string, and it is always written between quotes. 42 is a number, written without quotes.

The quotes matter. Compare these two lines:

print("2 + 3")
print(2 + 3)

The first prints the characters 2 + 3, because it is a string. The second adds the numbers and prints 5.

Arithmetic

Numbers can be combined with the usual symbols. * is multiply, / is divide, ** is "to the power of".

print(10 + 4)
print(10 - 4)
print(10 * 4)
print(10 / 4)
print(2 ** 10)

Notice 10 / 4 prints 2.5. Dividing always gives a number with a decimal point, even 8 / 4, which prints 2.0. Two more operators are worth knowing: // divides and drops the remainder, % gives only the remainder.

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

So 17 split into fives is 3 fives with 2 left over.

Nothing shows unless you print

Python computes 2 + 3 here but shows nothing, because nobody asked it to.

2 + 3

Run it: the box reports no output. Add print( and ) around it and run again.

Printing several things

print can take several values separated by commas. It puts a space between them.

print("Total:", 2 + 3)
print("apple", "bread", "milk")

Try it

Print three lines

Write a program that prints these three items, each on its own line, in this order:

apple
bread
milk

# Use three print() calls.

Receipt line

Three apples at 40 each. Print the total on one line, exactly like this:

Total: 120

Let Python do the multiplication rather than typing 120 yourself; that is the skill being practised.

print("Total:", ...)

Split the bill

A bill of 100 is split equally among 4 people. Then, separately, 20 eggs are packed into boxes of 6.

Print three lines: each person's share, how many full boxes you can pack, and how many eggs are left over.

25.0
3
2

print(100 / 4)
print(...)
print(...)

Next: Names.