Can You Solve This Math Problem?

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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.

And if you want to learn how to do complicated math in your head faster than most can with a calculator, Click Here!

Published or Updated: March 23, 2012
About Rob Berger

Rob founded the Dough Roller in 2007. A litigation attorney in the securities industry, he lives in Northern Virginia with his wife, their two teenagers, and the family mascot, a shih tzu named Sophie.

Comments

  1. Rob says:

    How about…

    1+2+3+4+5+6+7+(8*9)

  2. DR says:

    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.

  3. Al Brockman says:

    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”

    • rashel says:

      how they solve this porblm?? may i hav the code? i want the code for number 2 problm, i try to do this with c language,but i cant do . can u help me?

    • rashel says:

      how they solve this porblm?? may i hav the code? i want the code for number 1 problm, i try to do this with c language,but i cant do . can u help me?

  4. DR says:

    Al, very, very nice. Now if I can just think up a great article with the title, “Just Plug & Chug.”

  5. Sara says:

    One more (many possible variations):
    1 + ((2 + 3 + 4 – 5 + 6 – 7 + 8) * 9) = 100

    • jessa mae maban says:

      WHAT A NICE QUESTION THAT I CANT ANSWER…….HAHAHAH…

  6. Sara says:

    obviously, that should be an 8 then ) — not a “cool face”

  7. DR says:

    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.

  8. Linda says:

    What is the future value, if the present value is $1 and the interest
    rate is 2% annually after 7 years?

    • sumeet bal says:

      the future value is 1.5

    • Swapnil Chalke says:

      after the 7 year future value will be 1.14

  9. Linda says:

    what is the future value, if the present value is $5 and the
    interest rate is 3% annually after 10 years?

  10. Linda says:

    You have a savings account with $100 earning 4% annually. What
    would the value of this account be after 30 years?

    • DR says:

      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.

  11. Mike says:

    Find the numbers

    Use each of the digits 0-9 only once, to write five two digit numbers, which has the sum of 288

    • Cindy says:

      Did you ever find the answer? I need to know

  12. Erica says:

    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?

  13. sabrina says:

    i am receiving a $20 million which has to be divided among 270,000 people, so how much will we all receive?

    • GCH says:

      $740,740.74

  14. JRR says:

    Sabrina is it $20 million? :O

  15. Alberto Munoz says:

    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.

  16. Vickie says:

    12 divided by 5 1/3 =

  17. JNF says:

    What is 38-(-23-7.6-3^3*-17)?

  18. Rachel Greene says:

    use the numbers 1 thru 9 to solve.

    __ / __ x __ + __ x __ x __ / __ + __ x __ = 100

    • Brenda says:

      My 6th grader has the same problem. Nice to waste time on this :-( Sorry I do not have an answer either.

  19. Rachel Greene says:

    each # is to be used only once.

    • Brenda says:

      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

      • brittany says:

        where u get those answers?

        • Alyssa Breana says:

          um good question lol :D

  20. Brian says:

    use all 9 numbers only once to create a fraction that equals 1/3 (1, 2, 3, 4, 5, 6, 7, 8, 9)

  21. a13x4nd7u says:

    -1+2*3*4+5*6+7*8-9

  22. hannah says:

    1/2+3/5+1/6=

  23. Md. Badsha Faysal says:

    I have a book named “Foundations of Financial Management”.
    Author: Stanley B. Block and Geoffrey A. Hirt (12th Edition).

    In this book, there have a lot of problems of math. It has no solution. So, I need specific solution of Chapter-6: Working Capital & Financing Decision. Problems No: 7, 9, 10, 11, 12 & 13.

    If you provide me, I will be grateful to you.

  24. Md. Badsha Faysal says:

    Solve these problems that are given below.

    1. Stern Educational TV, Inc., has decided to buy a new computer system with an expected life at three years at a cost of $200,000. The company can borrow $200,000 for three years at 12% annual interest or for one year at 10% annual interest.

    a. How much would the firm save in interest over the three year life of the computer system if the one year loan is utilized, and the loan is rolled over (reborrowed) each year at the same 10% rate? Compare this to the 12%, three year loan.

    b. What if interest rates on the 10% loan go up to 15% in the second year and 18% in the third year? What would be the total interest cost compared to the 12%, three year loan.

    2. Assume that Atlas Sporting Goods, Inc., has $800,000 in assets. If it goes with a low-liquidity plan for the assets, it can earn a return of 15%, but with a high-liquidity plan the return will be 12%. If the firm goes with a short-term financing plan, the financing cost on the $800,000 will be 8%, and with a long-term financing plan, the financing cost on the $800,000 will be 10%.

    a. Compute the anticipated return after financing costs with the most aggressive asset-financing mix.

    b. Compute the anticipated return after financing costs with the most conservative asset-financing mix.

    c. Compute the anticipated return after financing costs with the two moderate approaches to the asset-financing mix.

    3. Lear, Inc., has $800,000 in current assets, $350,000 of which are considered permanent current assets. In addition, the firm has $600,000 invest in fixed assets.

    a. Lear wishes to finance all fixed assets half of its permanent current assets with long-term financing costing 10%. The balance will be financed with short-term financing, which currently costs 5%. Lear’s earnings before interests & taxes are $200,000. Determine Lear’s earnings after taxes under this financing plan. The tax rate is 30%.

    b. As an alternative, Lear might wish to finance all fixed assets and permanent current assets plus half of its temporary current assets with long-term financing and the balance with short-term financing. The same interest rates apply as in part b. Earnings before interests & taxes are $200,000. What will be Lear’s earnings after taxes? The taw rate is 30%.

  25. swagger crazy says:

    what is the answer (x+8)(8+x)

    • sohrab says:

      (8+x)^2=x^2+16x+64

  26. naviffir says:

    my math question :
    we have 1oo coins that one side them is white and the other side is black .
    we put 7 of the coins in white side and the others (93) in black side .
    now we want a blind person to divide the coins into X parts that the number of white coins in all the parts be the same .
    how can the blind person do that ?
    I will wait for your respond , thanks .
    naviffir

  27. Dave says:

    1+2+3=4
    the way to do this is set it up with straws or sticks or something and you only can move on stick to get it equal to 4

  28. Dave says:

    1+2+3=4
    the way to do this is set it up with straws or sticks or something and you only can move one stick or straw to get it equal to 4

  29. marie jeanette zacarias says:

    adding and subracting fractions.. can you explain it to me how did you get the 14
    7/9 +1/8-1/6= 14/18+1/18-3/18
    =14+1+3/18

    =12/18
    =2/3
    can you explain it to me how you solve it thanks

  30. Jennifer Carter says:

    __ / __ x __ + __ x __ x __ / __ + __ x __ = 100

    What is the answer to this question? I have to use 1-9 whole numbers and only each number twice

  31. John says:

    I need to solve this math problem …

    using numbers from 1 to 9 ( 1,2,3,4,5,6,7,8,9)

    __ __ X __ __ __ = __ __ __ __
    the numbers should not repeat, and it should be between 1 to 9 only.

  32. anda says:

    if sale amount is 300080 and profit margin is 6% and expense is 2.5% what will be the net profit

  33. robert says:

    A surveyor measured a triangular plot of ground and reported three angles as being 58.2 degrees, 70.0 degrees and 61.1 degrees. How much of an error did the surveyor make?

  34. batool says:

    evaluate each expression.
    1_(-2)+3=
    2_(-3)+5+(-5)+12
    how do u solve this and thx

  35. Lori Stark says:

    Please work out 10 divided 1/3

  36. Joselyn says:

    Using four’s 8′s and any mathematical operation , how can I create the numbers 1-25

  37. Albert says:

    Challenge for All

    590822 (?) (?) = 302259

    (?) 1 question mark for sign and (?)2 question mark for value

    • BAKARE says:

      (?)1 question mark is a negative sign(-)
      (?)2 question mark is 288563

      Life is that simple but COMPLICATED….**cheerzz**

    • BAKARE says:

      (8+8)/(8+8)=1
      (8/8)+(8/8)=2
      (8+8+8)/(8)=3
      (8*8)/(8+8)=4

      8-[(8+8)/8]=6
      [(8*8)-8]/8=7
      8+[(8-8)*8]=8
      [(8*8)+8]/8=9
      8+[(8+8)/8]=10

      i wuld leave d rest 2 u guyz…. i didnt get 5 though
      **cheerzz**

  38. shawnm says:

    use the numbers 3,5,6,2,54 and 5 in that order to write and expression that has avalue of 100

  39. shawnm says:

    please could you solve to me this math problem

    use the numbers 3,5,6,2,54 and 5 in that order to write and exprassion that has value of 100.

    thank you

  40. Kate says:

    How do you solve this? Q (1/4)=?? HELP

  41. aman says:

    principle 1000
    rent 12% p y
    time 3 years
    get the amount & C I

  42. lara says:

    __*_=__+__=__ complete the equation only 1 to 9. no repetition

  43. BILL says:

    CAN YOU SOLVE THIS??

    A developer sell 2 lots that are each 60 X 100 for $20 per square foot each. On the first lot she makes a 20% profit. On the second lot, she suffers a 20% loss. Calculate her net profit or loss.

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