Addition: Adding to a Sum or Total
Addition is used when combining items, or putting items together to obtain a total. It helps answer questions such as "How many?" "How much?" or "How far?" Let's look at different ways that addition can be used. Some words used often to refer to addition are "plus", "and", "the sum of", "total", or "added to".
Example 1 - Pedro's crew has 4 pulaskis. Jane's crew has 6 pulaskis. How many pulaskis do they have together?
As shown the the figure above, the addition needed to answer this question is: 4 + 6 = 10.
Addition is used in combining distances or lengths.
Example 2 - Crew 1 constructs 14 chains of handline on the day shift. Crew 2 constructs 11 chains of handline on the night shift. How many chains did crew 1 and 2 construct altogether?14 chains + 11 chains = 25 chains
Addition is used to find the distance around an object.
The total distance around an object is called the perimeter.
45 chains + 36 chains + 28 chains + 29 chains + 110 chains = 248 chains
Addition is used in combining areas.
Example 4 - The day shift had two spot fires that were contained at 6 acres and 8 acres each. What was the total area of the spot fires that burned during the day shift?
Addition is used in combining volumes.
Example 5 - Herman pumped 30 gallons of fuel into one tank, 25 gallons into the next tank, and 27 gallons into the last tank. How many gallons of fuel did Herman pump?
Addition is used in combining larger numbers.
When adding several numbers, especially large numbers, add the ones (1s) first, then the tens (10s), then the hundreds (100s), and so on.
Adding Positive and Negative Numbers
Numbers can be positive or negative. Positive numbers are indicated with a + sign, or have no sign. If a number is written without a sign, the sign is assumed to be positive. Negative numbers are indicated with a - sign. For example, a negative pressure may be indicated as -25 inches of Hg, or as a vacuum of 25 inches of Hg.
Example 7 - Adding numbers with like signs.
Example 8 - Adding numbers with unlike signs. Notice that the sign of the larger number is the sign that the answer will have.