## Sometimes the Trick Isn’t Mathematical
That’s another reason these puzzles are so effective.
The challenge may not require complicated arithmetic.
It may simply require recognizing that the question has been interpreted incorrectly.
For example, suppose a puzzle asks:
“Someone was 20 years old in 1990. How old were they in 2020?”
The answer is obviously:
[
2020-1990=30
]
The person’s age in 1990 is not the number of years that passed.
The elapsed time is 30 years.
Their age in 2020 would be 50.
Now you can see how a puzzle could encourage someone to write “50 years” when the question actually asks for the **number of years between two dates**.
Both numbers may be mathematically correct in different contexts.
Only one answers the question.
## The Importance of Context
Words such as **“ago,” “after,” “before,” “between,” “today,” “then,”** and **“when”** can completely change a calculation.
Consider:
“John is 50 today.”
“John was 50 ten years ago.”
Those statements obviously describe different situations.
Similarly:
“Fifty years ago” refers to a period of time.
“Fifty years old” refers to someone’s age.
The numbers are identical.
The meanings aren’t.
## Don’t Calculate Before Understanding
A common mistake is reaching for a calculator too quickly.
Calculators are excellent at arithmetic.
They cannot determine what the question means.
If you enter the wrong operation, the calculator will give you a perfectly accurate answer to the wrong problem.
That’s why these viral riddles are often solved mentally.
The hard part isn’t the arithmetic.
It’s interpretation.
## Why We Should Slow Down
