Have you ever seen a math problem that looks extremely simple at first glance?
Many people answer it in just a few seconds without thinking carefully.
However, most of them end up with the wrong answer!
Let us take a close look at the puzzle about Sarah.
The puzzle says: Sarah was asked her age. She answered: 110 – 10 x 10 + 10. How old is Sarah?
At first, this looks like a basic arithmetic problem from primary school.
To find Sarah’s real age, we need to solve the math expression following the correct order of operations.
In mathematics, there is a fundamental rule called standard order of operations.
This rule tells us which calculation to perform first, second, and last.
The rule states that multiplication and division must always be done before addition and subtraction.
When operations have the same priority level, we simply calculate from left to right.
Let us write down the full expression again: 110 – 10 x 10 + 10.
Now, let us follow the correct mathematical steps together.
First, we must look for any multiplication or division in the expression.
We see the multiplication part: 10 x 10.
We calculate 10 x 10, which equals 100.
Now, we replace 10 x 10 with 100 in our original expression.
The expression becomes: 110 – 100 + 10.
Second, we look at the remaining operations, which are subtraction and addition.
Since subtraction and addition have the exact same priority level, we work strictly from left to right.
The first operation on the left is 110 – 100.
We calculate 110 – 100, which gives us 10.
Now, our expression simplifies to: 10 + 10.
Finally, we perform the last remaining operation: 10 + 10.
When we add 10 and 10 together, we get 20.
Therefore, the final and correct result of the expression is 20.
This means that Sarah is 20 years old!
Why do so many people get this puzzle wrong?
Many people make the mistake of solving the operations straight from left to right without thinking.
They calculate 110 – 10 first to get 100.
Then, they multiply 100 x 10 to get 1000.
Finally, they add 10 to get 1010, which is completely incorrect!
Other people make a different mistake by doing the addition at the very end first.
They add 10 + 10 at the end to get 20, and then subtract 100 – 20, which is also wrong.
Math rules exist so that everyone in the world gets the exact same correct answer.
By following the standard order of operations step by step, we avoid all confusion.
Now you know how to solve this famous logic puzzle correctly.
Sarah is proudly 20 years old!
