Sign In
| 10 Theory slides |
| 10 Exercises - Grade E - A |
| Each lesson is meant to take 1-2 classroom sessions |
Here are a few recommended readings before getting started with this lesson.
But Kriz thinks that the multiplication should be done first. This is how Kriz evaluated the operations.
A numeric expression, or numerical expression, is a sequence of mathematical operations that only involves numbers. Consider the following examples.
Example | Is It a Numeric Expression? |
---|---|
5+3−2⋅8 | ✓ |
(9+12)3−4⋅7 | ✓ |
73+[(5−1)⋅(7+4)]5−71 | ✓ |
9w2+4s+7 | × |
1125 | × |
Select whether each given expression is a numerical expression or not.
Expression | Simplified | Operation |
---|---|---|
(1+2)⋅32−25+5 | 3⋅32−210 | Evaluating Parentheses and Grouping Symbols |
3⋅32−210 | 3⋅9−210 | Exponents |
3⋅9−210 | 27−5 | Multiplication and Division |
27−5 | 22 | Subtraction |
There are a few things to note about this evaluation.
To remember the order of operations, it is useful to memorize the acronym PEMDAS. Each letter of PEMDAS indicates a set of operations. A fun sentence to remember this acronym is Please Excuse My Dear Aunt Sally.
While waiting for baseball practice to start, Zain passed the time by counting how many people arrived to the field to practice and how many people left the field.
When Zain arrived and started counting, there were 9 people on the field practicing. Before Zain's practice started, two groups of three people left and four groups of six people arrived to the field. Then Zain's practice started.
Zain's baseball team needs new equipment before the season starts. Since Zain lives close to a good baseball equipment store, they were in charge of checking the prices. They noted these prices in a table.
Item | Price |
---|---|
Bat | $200 |
Glove | $95 |
Uniform | $130 |
Zain's team need 2 new bats, 8 new gloves, and 4 new uniforms. Luckily, there is a sale going on where bats and gloves are half their regular prices. Zain also has a $100 discount coupon that they will give the coach for equipment.
Zain is having a great time at bat in today's baseball game. He is hitting every single ball!
Multiply 0.87 by 147
Multiply 127.89 by 2.75
Round to nearest integer
Write the value of each given numerical expression. Remember the order of operations!
We want to find the value of the given numerical expression by using the specified order of operations. 3 + 5 * 4 We are told to add first, then to multiply. To make things easier, let's find the addition by itself first. 3 + 5 = 8 The two numbers add up to 8. We can substitute 8 for the addition in the expression so that we have the multiplication alone. 3 + 5 * 4 ⇓ 8 * 4 Now let's find the final value of the expression. 8 * 4 = 32 Therefore, if we follow the given order, the value of the expression is 32.
This time we want to do the multiplication first, then add. We will do something similar to what we did in Part A by calculating the multiplication first.
5* 4 = 20
Now substitute 20 into the expression for the multiplication expression. This will result in an expression with a single addition.
3 + 5 * 4
⇓
3 + 20
Let's perform the addition to find the result!
3 + 20 = 23
The result of evaluating the expression with this order is 23. It is different from the result from Part A!
To determine the correct result, we need to remember the order of operations. The acronym PEMDAS that helps to remember it.
If we consider the order, we can see that the M for multiplication goes before the A for addition. If we follow the order of operations, we need to multiply first, then add. We did this in Part B, which means that the correct result is 23!
We are given a numerical expression. We want to insert grouping symbols — parentheses — so that the expression has a value of 5. 1/4 * 32 - 12 There should be at least two numbers and an operation inside the parentheses for the grouping to make any changes to the value of the expression. There are two ways we can do this with the given expression. (1/4 * 32) - 12 [0.8em] 1/4 * (32 - 12) According to the order of operations, expressions inside parentheses should always be evaluated first. This is why the parentheses can affect the value of the expression. Here we can see what we simplify next.
Note that operations that are from the same step are performed from left to right. Now let's use these rules to simplify the two expressions, starting with the first one.
(1/4 * 32) - 12
Let's do it!
Operation | Before Simplification | After Simplification |
---|---|---|
Multiplication | ( 1/4 * 32) - 12 | ( 8) - 12 |
Subtraction | 8-12 | -4 |
The expression simplifies to - 4. This is not our target value, so let's move on to the second one. 1/4 * (32 - 12) Let's simplify it while keeping the order of operations in mind!
Operation | Before Simplification | After Simplification |
---|---|---|
Subtraction | 1/4 * ( 32 - 12) | 1/4 * ( 20) |
Multiplication | 1/4 * 20 | 5 |
This time the expression does equal 5. Now we know how we need to rewrite the expression with parentheses! 1/4 * (32 - 12)
According to the order of operations, expressions inside parentheses are evaluated first, followed by exponents, then multiplication and division, and finally addition and subtraction. Let's carefully consider the given expression. 11 + 3* 7^2 - 59 For the given expression, we will evaluate the exponent first, the multiplication next, and then the addition and subtraction last. Let's do it!
Operation | Before Simplification | After Simplification |
---|---|---|
Exponent | 11 + 3* 7^2 - 59 | 11 + 3* 49 - 59 |
Multiplication | 11 + 3* 49 - 59 | 11 + 147 - 59 |
Addition | 11 + 147 - 59 | 158-59 |
Subtraction | 158-59 | 99 |
The expression is equal to 99.
We can also evaluate this expression using a calculator. To do so, we type the given expression in the window of the calculator, then press Enter.
The result is the same, so we know our answer is correct.
According to the order of operations, expressions inside parentheses are evaluated first, followed by exponents, then multiplication and division, and finally addition and subtraction. Let's carefully consider the given expression. 3 * [(81-27) * 3 ] For the given expression, we will evaluate the expression inside the square brackets completely before evaluating the product outside the square brackets. Remember to follow the order of operations inside the square brackets as well! (81-27) * 3 Let's evaluate the difference inside parentheses first, then the product.
Operation | Before Simplification | After Simplification |
---|---|---|
Subtraction | 3 * [( 81- 27) * 3 ] | 3 * [ 54 * 3 ] |
Multiplication Inside Brackets | 3 * [ 54 * 3 ] | 3 * 162 |
Multiplication Outside Brackets | 3 * 162 | 486 |
The expression is equal to 486.
We can also evaluate this expression using a calculator. Type it into the calculator, then press Enter.
Whenever using a calculator for a complicated expression such as this, be very careful when placing the square brackets and the parentheses. A calculator will only do what it is told to do, not what you meant for it do!
Paulina needs to read 3 chapters of a book in a week. We can find the number of pages Paulina needs to read every day by solving the given numerical expression. 3* 14 ÷ 7 To evaluate this expression, we need we need to use the order of operations.
Remember that the symbols * and * are used to indicate multiplication. The symbol ÷ is used to indicate division, and we can also interpret a fraction as a division of the numerator by the denominator. In our case, since there are no grouping symbols or exponents, we will start by multiplying 3 by 14. 3 * 14 = 42 Now let's divide this result by 7. 42 ÷ 7 = 6 This means that Paulina needs to read 6 pages a day to stay on schedule for her assignment!