The online community is crazy about this math problem that is all addition but causes "brain twisting"

(Dan Tri) - A simple math problem that tests math skills and the ability to recognize patterns is confusing netizens. Can you solve this problem?

A math problem that is causing a stir in the online community requires those who want to try to find a solution to identify the pattern of a series of numbers that do not follow the usual rules of arithmetic. The problem requires us to have creative thinking to find the right pattern.

At first glance, the problem looks like four basic addition problems, with three already solved and only one left unsolved. But these are not ordinary addition problems, because the three available results are clearly wrong, according to the addition rules we learned in elementary school.

The problem is causing a stir in the online community (Photo: DM).

So the key to solving this math puzzle is not to find the right answer, but to find the pattern that produces the "wrong answer" that is correct for this particular problem. To do that, you need to recognize the commonality between the numbers before and after the "=" sign. Try to solve this problem, what is the answer you get?

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Solution

The problem began circulating on social media after Bholanath Dutta shared it on the X platform earlier this week. Hundreds of people commented on Dutta’s post, but only a few managed to come up with the correct answer.

Many people, even though they don't give the correct answer, have understood the hidden rules to some extent, they just haven't done it correctly.

The first step to finding the hidden pattern in these additions is to identify what the numbers have in common.

Many of you must have realized that each number after the "=" sign has a result that is 20 units greater than the previous number:

32 + 20 = 52

52 + 20 = 72

If you follow this rule, the answer you need to find will be 92. Many people give this answer, but there is an important flaw in this way of reasoning. That is, you have ignored the common point of the numbers to the left of the "=" sign.

If you look closely, you will see another rule. Specifically, the numbers to the left of the "=" sign that appear in the first three additions are written in the order 11 and 12, 12 and 13, 13 and 14.

The "trap" of the rule lies here. The addition in the fourth row breaks this rule, instead of writing "14 + 15", the addition in the fourth row jumps straight to "15 + 16". Many people realize this and give the answer 112 .

They deduced that this was a leapfrog addition, so they needed to add 40 units to the number 72 to get the answer 112. But this was still not the correct answer.

The correct rule of thumb is... calculate the usual way:

11 + 12 = 23

12 + 13 = 25

13 + 14 = 27

15 + 16 = 31

Do you see a pattern? The correct results of the first three additions all have the same two digits as the number after the "=" sign, just in reversed order.

Specifically:

23 is reversed to 32

25 is reversed to 52

27 is reversed to 72

The correct result of the 3 additions is written in reverse, this is the key logic of the problem (Photo: DM).

Applying this rule to the 4th addition, we have:

15 + 16 = 31

Reverse the number 31 to get the number 13.

So the correct answer to this problem is 13 .

The desired result of the "brain-twisting" problem (Photo: DM).

The hidden calculation rule in this puzzle is: Add the 2 numbers to the left of the "=" sign, then reverse the digits of the sum to get the result to the right of the "=" sign.

Source: https://dantri.com.vn/giao-duc/cong-dong-mang-phat-sot-voi-bai-toan-chi-toan-phep-cong-ma-gay-xoan-nao-20250320113006716.htm