Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. Unit 2 Addition of Whole Numbers 9 Mark the Answer When you arrive at a fi nal answer, mark it in a very clear manner. Try boxing it in, like this 248 , or double underlining it 248. This is especially important if you have several numbers on a sheet mixed in with previous, unrelated calculations. This is sometimes the situation when doing calculations in the shop or in the fi eld. Denominate Numbers Just as important as marking the right number is including the right unit in the answer. When marking answers, be aware of denominate numbers. If a question is expressed in inches, your answer should also be in inches. When adding denominate numbers, be certain that all the numbers have the same unit. Only denominate numbers having the same type of unit can be added. If an addition equation contains denominate numbers with dissimilar units, decide which unit is the most convenient for addition. Convert the numbers to the conve- nient unit. Then add the numbers. Compatible Units Incompatible Units 4″ 9 cm + 7″ + 4″ 11″ The equation with 9 cm and 4″ cannot be calculated as it is. One of these denominate numbers must be converted to the other denominate number’s unit of measurement. Then this equation can be completed. Conversion between different units will be covered later in the text. This concept of sharing common units is also applicable to subtraction equa- tions. Denominate numbers must have the same units in order to subtract from one another. To refresh the concept of denominate numbers, review the Denominate Numbers section in Unit 1.