Integer Word Problems

Integer Word Problems

Concept

An integer is defined as a number that can be written without a fractional component. For example, 11, 8, 0, and −1908 are integers whereas √5, Π are not integers. The set of integers consists of zero, the positive natural numbers, and their additive inverses. Integers are closed under the operations of addition and multiplication.

We use integers in our day-to-day life like measuring temperature, sea level, and speed limit. Translating verbal descriptions into expressions is an essential initial step in solving word problems. Deposits are normally represented by a positive sign and withdrawals are denoted by a negative sign. Negative numbers are used in weather forecasting to show the temperature of a region. Solving these integers word problems will help us relate the concept with practical applications.

Rules

Adding Integers
1. Rearrange the terms so that integers with the same sign are next to each other.
2. Add integers with like signs together.
3. Subtract the absolute values of integers with different signs.
4. The sign of the solution will be the sign of the larger integer.

Subtracting Integers
1. Rewrite the problem by changing the second term to its additive inverse.
2. Add the values.

Multiplying Integers
1. Multiply the absolute values of the integers.
2. If the two factors have the same sign, the product is positive.
3. If the two factors have different signs, the product is negative.

Dividing Integers
1. Divide the absolute values of the integers.
2. If the two integers have the same sign, the quotient is positive.
3. If the two integers have different signs, the quotient is negative.

Example

The price of one share of stock fell 4 dollars each day for 8 days. How much value did one share of the stock lose?

Solution

The stock price fell, so it is represented by -4. This happened for 8 days.
-4 x 8 = -32
The stock’s value dropped by $32.

Practice Integer Word Problems

Practice Problem 1

Write the expression that models the situation and then solve.
Abraham poured 15 kg of sand into his sandbox. Scott used 7 kg filling sandbags, Tess refilled the sandbox with 20 kg of sand. How much sand is in the sandbox.
 Integer Word Problems Example - Practice Problem 1

Practice Problem 2

Write the expression that models the situation and then solve.
The temperature was 15 °C and then dropped to -3 °C. Find the difference between the maximum and minimum temperatures.
 Integer Word Problems Example - Practice Problem 2

Practice Problem 3

A football team loses 3 yards every 1 minute. How many yards did they lose in 12 minutes?
 Integer Word Problems Example - Practice Problem 3

Practice Problem 4

If the temperature changes -21 degrees, in equivalent amounts over 7 days, how many degrees does the temperature change each day?
 Integer Word Problems Example - Practice Problem 4

Integer – whole numbers and their opposites {…, -3, -2, -1, 0, 1, 2, 3, …}

Negative integer – any integer less than zero.

Positive integer – any integer greater than zero.

Absolute value – the positive distance that a number is from 0 on a number line.

Zero Pair – a yellow counter and a red counter that represents zero.

Opposites – two integers that are the same distance from 0 on a number line but in opposite directions, like -5 and 5.

Additive inverses – two integers that are opposites.