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Some math questions are simple and can be answered easily.
See this math challenge 20 and its answer in the comment.
But a twist of the questioning will and can make it more challenging without changing the math expression.
Below is one:
Base on math challenge 20, if all unknowns **CANNOT** be repeated, what are they?
Again they are integers and below 10.
Enjoy the math thrill answering this.
Merry Christmas!
^.^
'

Can anyone come out the answers for A, B, C and D in the below math expression?
A

^{2} + B

^{2} + 2C

^{2} = D

^{2}
The rule is that the unknowns are all integers and below 10.
Happy trying, and
don't forget that maths is interesting!
:-)
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Percentage problems can be tricky at times when you are careless.
Let's us look at one maths word problem related to it.
Question:
There are 3 persons, John, Mary and Jane.
John is richer than Mary by 10%, and Mary is richer than Jane by 20%.
Is John richer than Jane by (10 + 20)% = 30% ?
Most students, upon quick thinking, will acknowledge that 30% is the correct answer.
Is it so?
To verify the answer, let us assume that Jane has $1000.
As such, Mary will have (100+20)% of $1000 = 1.2 x $1000 = $1200.
John is then 1.1 x $1200 = $1320 richer than Jane ==> By 32%.
If 30% is correct, we should get 1.3 X $1000 = $1300.
The latter number (dollar) is not the same as the first worked out solution.
Why?
**Mistake in understanding what is percentage:**
**To assume that John is 10% + 20% richer than Jane is incorrect.**
**This is due to the fact that percentage has to take a common reference for this to be correct.**
In the word problem, the percentages of comparison are not to a common reference.
The first one is to Mary, while the next is to Jane.
These made the denominator of the ratio different.
Thus adding the percentage up is a mistake, and an easy one too!
.