Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. xvi Section 1 Whole Numbers SECTION 1 Whole Numbers After studying this section, you will be able to: ▪ Practice good math work habits. ▪ Explain the Arabic number system. ▪ Round off whole numbers. ▪ Defi ne what is meant by a denominate number. ▪ Perform addition of whole numbers. ▪ Perform subtraction of whole numbers. ▪ Perform multiplication of whole numbers. ▪ Perform division of whole numbers. ▪ Check answers for four operations. Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. Name __________________________________ Date _____________ Class _______________ 1 UNIT 1 Introduction to Whole Numbers Key Terms approximate numbers Arabic number system decimal number system denominate numbers place value rounding Introduction A mastery of mathematics is one of the skills expected of you as a welder. For- tunately, the method of acquiring math skills is no different than any other skill. You learn the principles and then practice them in repeated applications until they become second nature. What about the questions ”Do I need to know math if I know how to use a cal- culator?” and “Is it necessary to develop a skill in mental calculation and a mastery of math facts?” There are practical reasons why the answer to these questions is yes. First, your employer and supervisor will expect you to be knowledgeable in math. They will expect that, as a tradesperson, you will bring basic math skills and knowledge of math facts to the job. If you begin your training in math by relying on a calculator, you will do yourself a great disservice. A calculator does not give you the confi dence and understanding that comes with building a skill. Also, when a group of welders is discussing the math aspects of a job (dimen- sions, weights, volumes, costs, etc.), you must be able to understand and contribute to the discussion. If your math skills are weak, you will likely feel uncomfort- able about joining in on this part of your work. Besides, there is certain admira- tion granted to a tradesperson by fellow workers who recognize that the person is clearly profi cient in math. Math Work Habits Although math is almost entirely a mental activity, there is a small but important tangible component to it. All your calculations, dimensions, and notes must be readable. Correct results are, of course, the fi nal product of math, but the calcula- tions should be done with a high degree of neatness and care. Orderly work in math is an important factor in arriving at correct answers. The following are some useful suggestions: ▪ Write your numbers fairly large. ▪ Write the numbers 4 and 9 carefully. When poorly written, these numbers are easily confused. anekoho/Shutterstock.com GUIDED TOUR Introduction introduces the subject matter of the unit, guiding the student on their learning path for the unit. Section Objectives clearly identify the knowledge and skills to be obtained when the units in the section are completed. Key Terms listed at the beginning of each unit are important terms to be learned. The terms are in bold/italic color type in the text and are defi ned in the Glossary.