## CS 1401, Quiz #4

Date: Tuesday, February 14, 2006
Class section (9 am or 10:30 am): ______________________
Name: ______________________________________________________________________

1. How did the invention of logarithms help computing?

```
Logarithms made computations easier because they enabled to reduce
multiplication to an easier operation - addition. The use of
logarithms in computing is based on the fact that log(a*b) = log(a)
+ log(b). So, to compute a*b, we can do the following:

1) find log(a) and log(b),

2) add these two logarithms, thus computing s = log(a)+ log(b); and

3) find a number whose logarithm is equal to this sum s.

This number will be exactly a*b.

This idea formed the base of a slide rule, which for several
centuries was the main computational tool of engineers.

```
2. At UTEP, a burrito costs \$1.50. Write a main method that asks a student for the number of burritos, and then computes the total and prints the statement:
```For (number) burritos, you pay \$(amount).
```
For example, if you ordered 5 burritos, the computer should print:
```For 5 burritos, you pay \$7.50.
```

Reminder: to read strings, you can define the input object as follows:

``` BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
```
to convert the string into an integer, you can use the method
```Integer.parseInt( )
```
the header of the main method is:
``` public static void main(String[] args) throws IOException{
```

```
public static void main(String[] args) throws IOException{