Developmental Math (NROC)

Introduction

Mathematics involves solving problems that involve numbers. We will work with whole numbers, which are any of the numbers 0, 1, 2, 3 and so on. We first need to have a thorough understanding of the number system we use. Suppose the scientists preparing a lunar command module know it has to travel 382, 564 kilometers to get to the moon. How well would they do if they didn’t understand this number? Do you think it would make more of a difference if the 8 was off by 1 or if the 4 was off by 1?

In this section, you will take a look at digits and place value. You will also learn how to write whole numbers in words, standard form, and expanded form based on the place values of their digits.

The Number System

A digit is one of the symbols is one of the symbols 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9. All numbers are made up of one or more digits. Numbers such as 2 have one digit, whereas numbers such as 89 have two digits. To understand what a number really means, you need to understand what the digits represent in a given number.

The position of each digit in a number tells its value, or place value. We can use a place-value chart like the one below to easily see the place value for each digit. The place values for the digits in 1, 456 are shown in this chart.

In the number 1, 456 the digit 1 is in the thousands place. The digit 4 is in the hundreds place. The digit 5 is in the tens place, and the digit 6 is in the ones place.

Periods and Standard Form

The standard form of a number refers to a type of notation in which digits are separated into groups of three by commas. These groups of three digits are known as periods. For example, 893, 450, 243 has three periods with three digits in each period, as shown below.

Let’s examine the number of digits and periods in a greater number. The number of body cells in an average adult human is about one hundred trillion. This number is written as 100, 000, 000, 000, 000. Notice that there are 15 digits and 5 periods. Here is how the number would look in a place-value chart.

Converting Standard Form to Word Names

We often use word names to write numbers. A word name for 42 is “forty-two.” The total number of weeks in a year, 52, is written as “fifty-two.” For whole numbers with three digits, use the word “hundred” to describe how many hundreds there are in the number. For example, for the number of days in a normal year, 365, the digit 3 is in the hundreds place. The word name for the number is “three hundred sixty-five.”