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Can You Solve This Math Problem?
I love stories about people who didn't give up. Miles Levin is such a story. Stories of perseverance help to motivate us in all aspects of our life, including our financial lives. But how do we teach perseverance to our kids? That was my challenge this weekend when my son was trying to solve a difficult math problem.
Using the numbers 1 through 9 in order, construct a math problem that equals 100.
Simple enough, right? If you can add, subtract, multiply and divide, you can solve this problem. When the answer didn't come easily to him, he wanted to give up. But through encouragement (ok, and some threats, too), he worked through the problem and solved it. I told him that life is a series of problems, just like this one. And at each step in life, you have a choice--give up or keep trying. And we answer that question every day, whether we realize it or not.
So can you solve the math problem? Leave a comment if you think you've got the answer. Oh, and here's a hint: You can use parentheses to change the order of operation.
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How about…
1+2+3+4+5+6+7+(8*9)
Rob, well done. What I like about this math problem is how simple the solution appears. There are other ways to solve the problem, by the way, so leave a comment if you have figured out these other alternatives.
I have three possible solutions – two from my son; one from my son-in-law. Here they are:
1.
100 = (1+2+3+4) x [(5-6) x 7 + 8 + 9]
2.
1-2*3-4+5*6+7+8*9 = 100. I like this because, though parentheses could be applied, you don’t need them if your order of operations is correct. I’m mucking around with something more creative (exponents are allowed, right?)
3.
I think I could come up with the simple ones with a C program (sigh – it was going to be a shell script, but C handles arrays better) — there are eight operands, and (presuming simple math plus exponents) five possibilities for each operand: + – * / ^, which means 5^8 combinations, or 390625. All you have to do is build a 390625 row array with eight columns, each row representing a possible combination. Then you run something that translates, say,
1 1 1 1 1 1 1 1 into 1-2-3-4-5-6-7-8-9, and evaluates whether that equals 100.
After that, it’s, as my high school geometry teacher would say, “just plug & chug”
Al, very, very nice. Now if I can just think up a great article with the title, “Just Plug & Chug.”
One more (many possible variations):
* 9) = 100
1 + ((2 + 3 + 4 – 5 + 6 – 7 +
obviously, that should be an 8 then ) — not a “cool face”
Sara, very nice. This “simple” math problem reminds me that there are often multiple solutions to the same problem or challenge. Money is the same way. There are definitely many wrong answers. But there are also several paths that each can get us to our goals.
What is the future value, if the present value is $1 and the interest
rate is 2% annually after 7 years?
what is the future value, if the present value is $5 and the
interest rate is 3% annually after 10 years?
You have a savings account with $100 earning 4% annually. What
would the value of this account be after 30 years?
Linda, the answer will depend in part on the rate at which the interest compounds (daily, weekly, monthly, annually). But that said, my answer for this and your other questions is (in round numbers) $324.34, $6.72 and $1.15.
Find the numbers
Use each of the digits 0-9 only once, to write five two digit numbers, which has the sum of 288
You have been hired by a day care agency to fence in an are a to be used for a playground. You have been provided with 60 feet of fencing (in 4-foot sections) and a foot gate. How can you put up the fence so the children have the maximum amount of space in which to play?
i am receiving a $20 million which has to be divided among 270,000 people, so how much will we all receive?
Sabrina is it $20 million? :O
Dear Erica regarding your problem about the fence:
You have to use a rectangle of maximun area i.e. a square , the perimeter is 60 feet of fencing plus 1 foot of gate: all together 61 feet, you build a square with a side of 61/4 each.
12 divided by 5 1/3 =
What is 38-(-23-7.6-3^3*-17)?
use the numbers 1 thru 9 to solve.
__ / __ x __ + __ x __ x __ / __ + __ x __ = 100
My 6th grader has the same problem. Nice to waste time on this
Sorry I do not have an answer either.
each # is to be used only once.
Found this on the internet. Thanks to someone. Here is 25 of the 199 answers he had.
1 1/2*7+5*3*6/9+8*4
2 1/2*7+5*6*3/9+8*4
3 1/2*8+5*3*6/9+7*4
4 1/2*8+5*6*3/9+7*4
5 1/3*6+5*2*8/7+9*4
6 1/3*6+5*8*2/7+9*4
7 1/3*6+7*2*8/9+4*5
8 1/3*6+7*8*2/9+4*5
9 1/3*8+9*2*6/7+5*4
10 1/3*8+9*6*2/7+5*4
11 1/3*9+4*2*6/7+8*5
12 1/3*9+4*6*2/7+8*5
13 1/4*7+2*3*6/9+5*8
14 1/4*7+2*6*3/9+5*8
15 1/4*8+7*3*6/9+2*5
16 1/4*8+7*6*3/9+2*5
17 1/6*2+5*3*9/8+7*4
18 1/6*2+5*9*3/8+7*4
19 1/6*2+7*3*4/8+9*5
20 1/6*2+7*4*3/8+9*5
21 1/6*8+2*3*9/5+7*4
22 1/6*8+2*9*3/5+7*4
23 1/9*3+2*6*8/7+4*5
24 1/9*3+2*8*6/7+4*5
25 1/9*5+8*3*4/7+2*6
use all 9 numbers only once to create a fraction that equals 1/3 (1, 2, 3, 4, 5, 6, 7, 8, 9)