Math problems can be simple or complicated, long or short -- and sometimes they're even a little bit tricky. It can be challenging to solve brainteaser questions, even when they involve some mathematics. Don't let tricky questions confuse you. View them as a puzzle rather than a problem and you'll be able to solve them easily.
A Tricky Divide-by Problem
Take a seemingly simple math problem: Divide 50 by 1/2, then add 20. Many students will start solving by dividing 50 in half, yielding 25, and then adding 20 to get an answer of 45. But that's incorrect. Instead, take a look at the question: It says, divide 50 by 1/2 not divide 50 into 1/2. This means you'll need to divide 50 by 1/2 -- or 0.5 as a decimal -- to yield 100. Then add 20; so the correct answer is 120.
A "More Than" Question
If a bottle of soda costs $4.50, and the bottle costs $3 more than the soda, how much does the soda cost? A common mistake is to simply subtract $3 from $4.50, resulting in a cost of $1.50 for the soda. However, that's incorrect. To correctly set up this solution, create an equation, using "s" for the soda. You know that the bottle costs $3 more than the soda, so the bottle would be represented as s + 3, using the following steps:
- s + (s + 3) = 4.50
- 2s + 3 = 4.50
- 2s = 1.50
- s = 0.75
So the cost of the soda is $0.75. The bottle is $3 more than that, or $3.75.
A Consecutive Number Question
If the sum of 3 consecutive numbers is 213, what are the numbers? Some students might try to guess groups of numbers, which could take a while. Look at another strategy to solve the problem: Set up an equation for each number. Use "x" to represent the first number. Since you know they are consecutive numbers, the next number would be x + 1 and then the final number is x + 2. Set up an equation, then solve it as follows.
- x + (x + 1) + (x + 2) = 213
- 3x + 3 = 213
- 3x = 210
- x = 70
So the first number is 70. That means that the three numbers are 70, 71 and 72.
A Takeaway Question
How many times can you take 6 away from 36? Some students might jump to the answer of 6, but that's not correct. The question asks how many times you can take 6 away from 36. The correct answer is only once. After you take away 6 once, you don't have 36 any longer: 36 - 6 = 30. At that point, you're not taking 6 away from 36, you're taking it away from 30, then 24 and so on. So the correct answer is: just once.