How many questions can you solve without looking at the answer?
There are intuitive problems, just applying normal calculations will find the answer, but on the contrary, many problems pose trick questions, causing many people “brain pain” without being able to think of a question. reply. Here are 9 problems that have made the online community stir. How many questions can you answer?
What do you think the answer will be? The first solution is to add the result of the upper row with the number of the bottom row, we will have the result of the bottom row (1 + 4 = 5, 5 + 2 + 5 = 12,…), and so on, we will whose final number is 40.
However, there is still another solution, which is to multiply the second number in the calculation by the first number and then continue to add the first number (4 x 1 + 1 = 5, 5 x 2 + 2 = 12…), if calculated this way, the final answer will be 96 .
Is the result 1 or 9?
If according to what we learned in school, the result will be 9, according to the principle that the calculation in brackets is done first 2 + 1 = 3. Then, if the sequence of calculations consists of only subtraction and addition or subtraction. Multiplication and division must be done from left to right. Thus, the order is 6 : 2 x 3 = 3 x 3 = 9. This is the most common calculation worldwide and is the most accurate result “today”.
Why “today” The controversy arises because some people use an ancient calculation rule, common before 1917, that when using division, it is understood that the divisor is the sum of all numbers. The component is to the right of the symbol For example: x : 2y if calculated according to this rule will be x : (2y) Thus, the result of the above calculation will be 1 .
Multiplication is commutative, which everyone probably knows. 5 x 3 is similar to 3 x 5. However, the teacher gave the wrong answer to the above student’s work because… the program has not been taught yet. When appearing online, this teacher’s overly mechanical grading method made many people angry because it crushed children’s creativity and learning spirit.
This quiz comes from Singapore and has attracted great attention to the online community. From the given data, you have to guess the date of birth of Cheryl. If the correct information and exclusions are used, Cheryl’s birthday will be July 16.
At first, Cheryl only told Albert and Bernard only one information about the month and date of birth. Cheryl gives 10 results to exclude. Try to arrange them like the table below, it will be easier to exclude.
Now watch what Albert and Bernard exchange that both end up learning Cheryl’s birthday.
Albert: I don’t know your date of birth, but certainly not even Bernard.
The first part was obvious, Albert only knew the month of birth because Cheryl had said it first, but the second part was an important clue. Why does Albert know that Bernard does not know Cheryl’s date of birth, but after listening to Albert’s answer, Bernard knows:
“I didn’t know at first, but now I do.”
If Cheryl told Bernard it was the 19th or 18th, Bernard knew it was May or June without waiting for Albert’s words. Similarly, Albert claims that Bernard does not know because the number of months Cheryl revealed to him is not 5 and 6.
Thus, we have eliminated half of the answers, the remaining will be July 14, July 16, August 14, August 15 and August 17. We can continue to remove the 14th because there are two overlapping dates.
In the end, we are left with three answers, July 16, August 15, and August 17. Albert’s last words will be the key to solving the problem:
“Now I know Cheryl’s birthday.”
For Albert to say so, Cheryl’s birthday can only be in July because if it is August, there are still two possibilities.
Thus, Cheryl’s birthday is July 16 .
There were 19 people getting off the train at the first station. Another 17 people boarded the train. There are 63 people on board now. So, how many people were on board at first?
It sounds a bit headache, but you just need to write down the numbers and it will be easy to imagine: 19 people getting off the train can be interpreted as -19, adding 17 people is +17.
-19 + 17 = -2, which means that now the ship has lost two people compared to the original. The current number of people is 63, so the original number is 65 .
What number is the car in?
This is not a math problem, so don’t waste your time thinking of logical solutions, just turn the picture upside down and you will see that this is just the number 86 to 91 and the car is in box 87 .
This sentence is probably quite familiar. The problem is as follows: “A borrowed from his mother and from his father to buy a bag. After buying, A has 3 dollars left. A pays 1 dollar to mother and 1 dollar to father, keeping 1 dollar. Now A owes + = , plus his is . Where’s the remaining 1 dollar?”
Actually, not a dollar is lost here, because you just confused the words. The remaining cannot be included in the amount owed.
At first, A’s father has , A’s mother has , A has
Final:
Father A has 1 dollar + the amount of 49 dollars that A owes —> Father A still has 50 dollars
Mother A has 1 dollar + the amount of 49 dollars that A owes —> Mother A still has 50 dollars
A has 1 dollar + 1 bag (worth 97 dollars) + debt 98 dollars —> A has 1 + 97 – 98 = 0 dollars
So mom and dad at first each have 50 dollars, in the end they still “have” 50 dollars
A starts with 0 dollars but in the end still has 0 dollars.
“The bat and the ball cost .10. The bat is 1 dollar more expensive than the ball. So how much does the ball cost?”
More than 50% of the respondents answered 0.1 dollar, which is 10 cents. This is the wrong answer.
If the ball costs X copper and the club costs 1 USD more than it, we have club price = X + 1
According to the problem, we have ball+stick = X+(X+1) = 1.10
2X+1=1.10
2X=0.1
X = 0.05 dollars = 5 cents
Behavioral economist Daniel Kahneman explains why so many people get the answer wrong:
“This quiz immediately prompts a visual answer, but it’s wrong (10 cents). Try adding them together and you’ll see that if the ball costs 10 cents, the total cost of the ball and the club will be .20.” .
Fill in the numbers 1 – 9 (no duplicates) in the blanks on the snake worksheet above.
This isn’t a trick puzzle at all, just a waste of time by filling it out over and over until you find the right place to place the numbers. The problem has 362,880 possible numbers, but only a few correct answers.
To simplify the problem, let’s put it in the form of an equation with a, b, c, d, e, f, g, h, and i as the numeric entries. We will have:
a + (13b/c) + d + 12e – f – 11 + (gh/i) – 10 = 66
Can be shortened to
a + (13b/c) + d + 12e – f +(gh/i) = 66 + 11 + 10 = 87
Or:
a + d – f + (13b/c) + 12e +(gh/i) = 87
From here, we can determine that b/c and gh/i will be integers and 13b/c should not be too large.
There are many ways to fill in the correct answer, the Guardian site, there are more than 100 correct ways. Here is one of those ways shared by someone with the nickname Brollachain:
For the cluster 13b/c to be the smallest number, let b = 2 and c = 1. We will have:
a + d – f + 26 + 12e +(gh/i) = 87
Or:
a + d – f + 12e +(gh/i) = 61
Thus, we are left with the numbers 3-9, in which, 3, 5 and 7 are prime numbers, you need to fill them in first to avoid confusing the equation.
Let a = 3, d = 5 and f = 7.
Thus, we will have:
3 + 5 – 7 + 12e +(gh/i) = 61
Or:
12e +(gh/i) = 60
The remaining numbers are 4, 6, 8, 9.
Substitute back and forth, you will get the most reasonable filling of e = 4, g = 9, h = 8, i = 6
48 + (72/6) = 48 +12 = 60