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Variables, constants and operators
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Programs store values in variables and constants, then work on them with operators. Integer division and modulus come up in almost every exam.
Variables and constants
A variable is a named store whose value can change while the program runs.
A constant is a named value that does not change, such as VAT = 0.2.
Constants make code easier to read, and if the value ever changes you only edit it in one place.
A constant is a named value that does not change, such as VAT = 0.2.
Constants make code easier to read, and if the value ever changes you only edit it in one place.
Arithmetic operators in Python
Relational and logical operators
Relational: == (equal to), != (not equal to), <, >, <=, >=. They give True or False.
Logical: and, or, not combine True/False values.
(age >= 13) and (age <= 19) is True only for teenagers.
Remember: = assigns a value, == compares two values.
Logical: and, or, not combine True/False values.
(age >= 13) and (age <= 19) is True only for teenagers.
Remember: = assigns a value, == compares two values.
A school has 230 students and each minibus seats 16. Use integer division and modulus to find how many buses are full and how many students are left over.
- 230 // 16 = 14 full buses
- 230 % 16 = 6 students left over
Answer: 14 full buses and 6 students left over
Variables change, constants do not. // gives the whole-number part of a division and % gives the remainder. == compares, = assigns. and, or, not combine conditions.
The interactive lesson includes the diagrams for this topic.
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