Have you ever come across a math problem that seems easy at first glance, only to realize that most people get it wrong? The equation 9 – 9 ÷ 9 + 9 – 9 ÷ 9 = ? is one such puzzle that confuses many. It looks simple, but if you’re not careful, you might end up with the wrong answer.
Are you ready to put your math skills to the test? Take a moment to solve it before reading ahead. Think you got it right? Let’s find out!
Why Do So Many People Get This Wrong?
At first glance, this equation appears straightforward. However, small details in mathematical rules trip people up. Here are some common mistakes that lead to the wrong answer:
- Ignoring the Order of Operations (PEMDAS/BODMAS) – Many people solve the problem from left to right without following the correct order of operations.
- Misplacing Parentheses (Even When They Aren’t Written) – Some assume parentheses where there are none, changing how they approach division and subtraction.
- Rushing Through the Calculation – The problem is designed to look easy, so people tend to solve it quickly and overlook critical steps.
So, what’s the correct approach? Let’s break it down step by step.
Step-by-Step Solution
To solve this equation correctly, we must follow the order of operations. The most commonly used rule is PEMDAS (Parentheses, Exponents, Multiplication and Division (from left to right), Addition and Subtraction (from left to right)).
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The given equation:
9 – 9 ÷ 9 + 9 – 9 ÷ 9
Step 1: Solve the Division First
According to PEMDAS, division comes before subtraction and addition. So, let’s divide first:
- 9÷9=19 ÷ 9 = 19÷9=1
- 9÷9=19 ÷ 9 = 19÷9=1
Now, substitute these values back into the equation:
9 – 1 + 9 – 1
Step 2: Perform Addition and Subtraction from Left to Right
Now, we calculate in order from left to right:
- 9 – 1 = 8
- 8 + 9 = 17
- 17 – 1 = 16
So, the correct answer is: 16
Common Incorrect Answers and Why They Happen
Many people arrive at incorrect answers because they don’t follow the correct order of operations. Here are some of the most common mistakes:
- Answer: 0 – This happens when someone groups all the numbers together without following PEMDAS, incorrectly simplifying the problem as:
9−9−9+9−9=09 – 9 – 9 + 9 – 9 = 09−9−9+9−9=0 - Answer: 1 – Some mistakenly subtract 9 from itself first before dividing, leading to:
(9−9)÷9+9−9÷9=1(9 – 9) ÷ 9 + 9 – 9 ÷ 9 = 1(9−9)÷9+9−9÷9=1
These errors reinforce the importance of following the correct mathematical rules step by step.
Why Understanding Order of Operations Matters
You might wonder—why does it even matter? Well, mathematics is built on logical rules, and following them correctly ensures we get consistent, accurate answers. The order of operations is used in everything from programming to engineering to everyday calculations.
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Think about it this way: If a recipe tells you to bake a cake at 350°F for 30 minutes before adding frosting, you wouldn’t reverse the steps, right? Math works the same way—sequence matters!
Put Your Skills to the Test
Did you get the correct answer? Share your response in the comments! Were you surprised by how easy it was to make a mistake?
If you enjoy solving puzzles like this, challenge your friends and see if they can get it right! Math riddles help improve problem-solving skills and boost logical thinking.
Want more brain teasers like this? Keep testing yourself with tricky puzzles and improve your critical thinking skills! Who knows? The next time you see a math problem like this, you might be among the 10% who get it right on the first try!
9 things you should never plug into a power strip
When we think of the past, one of the first thoughts that runs through our mind is how people lived without electricity. Nowadays, we can’t even imagine a day without it because all of our appliances and devices run on electricity.
The truth is, however, that most homes don’t have enough power outlets to keep everything running and charged, so most of us rely on power strips without being aware that appliances that consume a lot of energy become dangerous fire hazards when we plug them into a power strip.
Although power strips are the thing to go to when it comes to charging your phone or power an entertainment setup, there are certain devices that should never be plugged into a power strip.
Air conditioners, space heaters, toasters, and other appliances that use high wattage can easily cause power strips to overheat, which can easily lead to a fire hazard.
Even before plugging anything into a power strip consider the ammount of power they support. This is usually listed on the product itself.
High-capacity appliances need to draw a lot of power through an electrical circuit to work. Keep in mind that an appliance does not need to be large in size to draw large amounts of power.
Below is the list of appliances that should never be plugged into a power strip.
1. The oven: Even though the oven is not used continually, it is a power-hungry appliance that should not be plugged into a power strip. In fact, it should be plugged into its own wall outlet on its own circuit.
2. Refrigerator: Refrigerators require a lot of power and frequently cycle on and off which can easily overload a power strip and cause damage. Much like the oven, refrigerators require a wall outlet dedicated solely to powering the appliance.
3. Washing Machine: When turned on, washing machines pull a lot of power. This is the main reason why these appliances shouldn’t share a receptacle with any other appliance or device.
Most washing machines use a max of up to 1400 watts, putting it dangerously close to the max load of most power strips. On top of that while working, washing machines are usually left unattended and work longer hours, at least an hour, which is long enough for a power strip to overheat.
4. Heating: Portable heaters should never be plugged into a power strip because most of them use 1,500 watts of energy on their high setting and they usually run for extended periods of time.
5. Microwave: Since they consume a lot of energy when used, most microwave ovens are plugged into their own receptacle and that is always a good practice.
6. Coffee Maker: Those who own a coffee maker are not fully aware of the power these appliances use, and this is why they should never be plugged into any sort of power strip or extension cord.
7. Toaster: You may think that browning up slices of bread or bagels doesn’t require a lot of energy, but the truth is that toasters use a lot of energy when in use and they should be plugged directly into the receptacle rather than a power strip.
8. Another Power Strip: Power strips are not meant to be used in conjunction with another power strip, although many people do exactly that. This, however, violates most safety codes because it can easily lead to overloading the electrical system.
9. Electronics (Computer, TV, Router): These types of electronic devices don’t necessarily use a lot of power on their own, but they are sensitive to surges and you can find yourself with a burnt out computer or TV very quickly if you plug them into a power strip.
If you want to protect these sensitive devices from power surges, opt for a power strip that functions as a surge protector.
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