Problem 11 - Thinking Mathematically

Question

Convert the numeral to a numeral in base ten. \(70355_{\text {eight }}\)

Step-by-Step Solution

Answer

The decimal representation of the octal number \(70355_8\) is \(30253_{10}\).

Step 1: Understanding Base

Normally, the numbers we use are in base ten, meaning each place represents a power of ten. However, in this case, the base is eight. This means that each place represents a power of eight. The rightmost place represents \(8^0\) (which equals 1), the next place represents \(8^1\) (equals 8), followed by \(8^2\) (equals 64), \(8^3\) (equals 512), and so on.

Step 2: Converting Each Digit

Starting from the right, multiply each digit by \(8^n\) where \(n\) is the position of the digit, starting at 0 for the rightmost place. In this case, the calculation becomes \(5 * 8^0\), \(5 * 8^1\), \(3 * 8^2\), \(0 * 8^3\), and \(7 * 8^4\).

Step 3: Adding Up

The result from each digit is added together to get the number in base ten. This results in the calculation \(5 + 40 + 1536 + 0 + 28672 = 30253\).

Key Concepts

Number Bases

Understanding different number bases is crucial for comprehending how numbers are represented in various numeral systems. In common usage, the base ten or decimal system is the standard, where numbers are composed of digits 0 through 9 and each position represents a power of ten. However, many other bases exist, such as binary (base two), octal (base eight), and hexadecimal (base sixteen).

When dealing with a non-decimal base, it's important to remember that the value of each digit is multiplied by the base raised to the power of its position, starting from the right with the exponent zero. For example, in the octal number system, the rightmost digit is multiplied by \(8^0\), the next by \(8^1\), and so on. This positional notation allows numbers in any base to be converted into decimal numbers by summing up these products.

Numeral Systems

A numeral system is the complete set of symbols and rules used to represent numbers. Common numeral systems include the aforementioned decimal, binary, octal, and hexadecimal systems. Each system has its own set of symbols (digits) and base that dictates how numbers are structured.

In the binary system, only two symbols, 0 and 1, are used. In octal, the symbols range from 0 to 7, and in hexadecimal, the symbols include 0-9 and A-F, with 'A' representing 10 and 'F' representing 15 in decimal. These systems are not only theoretical concepts; they have practical uses in various fields such as computing where binary is the foundation, and in digital electronics where hexadecimal provides a more human-readable format of binary-coded data.

Mathematical Notation

Mathematical notation is a system of symbolic representations of mathematical objects and ideas. This not only includes numbers and operations but also variables, functions, and relations. Efficient notation is essential for clear communication of mathematical concepts and for solving problems.

When converting from one base to another, we often denote the base of a number by writing it as a subscript following the number, such as \(70355_{eight}\) which indicates that the number is in base eight. As we work through conversions, we employ exponentiation to denote powers of the base, like \(8^0\), \(8^1\), and so on. Understanding and using these notations correctly is vital as it helps in carrying out operations accurately and in understanding the structure of numbers in different bases.