Chapter 10 Math 267
Add the ones column and carry over the 1 to the tens column. Then,
add the tens column, and carry the 1 to the hundreds column.
1 1
788
+ 57
845
Subtracting Whole Numbers
Subtraction is the opposite of addition. When numbers are subtracted,
one number is taken away from another. Simple subtraction is written
as 6 – 2 = 4, with the minus sign (–) indicating subtraction. The answer
obtained in a subtraction problem is called the difference. Subtraction prob-
lems can be written in two ways:
54
or 54 – 23 = 31 – 23
31
You can check your answer by adding the difference to the number
subtracted. If your answer is correct, your total will equal the fi rst number
in the equation. To check the above problem, 54 – 23 = 31, you would add
31 + 23 = 54.
Subtracting by Borrowing Numbers
Some subtraction problems require that you “borrow” a number. When
beginning a subtraction problem, align the numbers one on top of the other,
as you do during an addition problem. Look at the rightmost column. If the
Supply Inventory
1. Carlos works in a doctor’s offi ce. One day, he is asked to take inventory
of disposable offi ce surgery trays in the offi ce. He fi nds 10 trays in exam
room A’s closet, 8 in exam room B’s closet, and 24 in the supply cup-
board. How many trays are in the doctor’s offi ce?
2. Carlos is then asked to take inventory of boxes of alcohol swabs in the
offi ce. He counts 20 boxes in exam room A’s closet, 18 in exam room B’s
closet, 12 in the reception room drawers, and 9 in the supply cupboard.
How many boxes of alcohol swabs are in the offi ce?
3. Finally, Carlos must total the number of patients that were seen by the
doctor over the course of the week (5 days). There were 20 patients seen
on day 1, 35 on day 2, 40 on day 3, 34 on day 4, and 21 on day 5. How
many patients did the doctor see over the course of fi ve days?
Real Life Scenario
subtraction
the process of removing one
number from another num-
ber; the opposite of addition