# Use Linux terminal as a calculator

Linux provides several methods for calculating expressions using the command line.

## Using `bc`

— basic calculator for command line

`bc`

is a native Linux tool (originated on Unix systems in 1975) that stands for “basic calculator”. To use it, simply type `bc`

followed by an expression. To quit, type `quit`

.

```
1> bc
2Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.
3This is free software with ABSOLUTELY NO WARRANTY.
4For details type `warranty'.
55 + 5
610
725 * 4
8100
9100 / 2 * 35
101750
112 * (2 * 5) + 15
1235
13quit
```

Additionally, variables, arrays, algebraic expressions, etc. can be used. Refer to the `bc`

manual for more information.

## Using `expr`

The `expr`

command evaluates basic expressions.

```
1> expr 5 + 5
210
3> expr 25 \* 4
4100
5> expr 100 / 2 \* 35
61750
```

Keep in mind, it should be used for basic calculations. If something more advanced is required (like parenthesis), `bc`

or arithmetic expansion may be more suitable.

## Using arithmetic expansion

Arithmetic expansion evaluates an expression and substitutes the result. In combination with `echo`

, it can be used as a calculator.

```
1> echo "$((5 + 5))"
210
3> echo "$((25 * 4))"
4100
5> echo "$((100 / 2 * 35))"
61750
7> echo "$((2 * (2 * 5) + 15))"
835
```

## Using `qalc`

Qalc is a multi-purpose cross-platform desktop calculator. It provides versatility and supports many everyday needs: currency conversion, percent calculation, etc.

Install it on Ubuntu via `apt`

:

`1sudo apt install qalc`

Example usage:

```
1> sqrt(72)
2
3 sqrt(72) = 6 × √(2) ≈ 8.485281374
4
5> fibonacci(133) to hex
6
7 fibonacci(133) ≈ 0x90540BE2616C26F81F876B9
8
9> 5/3 + 3/7
10
11 (5 / 3) + (3 / 7) = 44/21 = 2 + 2/21 ≈ 2.095238095
12
13> 5 + 5
14
15 5 + 5 = 10
16
17> exit
```