Math Help

posted by .

Yes it was answered previously but I am sorry that I did not follow the pattern. I was told that the answer that I submitted was incorrect. Please help if you can. Thank you so very much.

THE PROBLEM READS:
A three-digit number increases by 9 if we exchange the second and third digits. The same three-digit number increases by 90 if we exchange the first and second digits. By how much will the value increase if we exchange the first and third digits?

Thank you

  • Math Help -

    in the original number,
    let the unit digit be a,
    the tens digit be b
    and the hundred digit be c
    the appearance of our number is cba
    then the value of our number is 100c + 10b + a

    case1: interchange 2nd and 3rd digit
    number looks like cab
    value of our new number is 100c + 10a + b
    so 100c + 10a + b - (100c + 10b + a) = 9
    9a -9b = 9
    a-b = 1 , (#1)

    case2: interchange the 1st and 2nd digit
    appearance of new number is bca
    value of new number is 100b + 10c + a
    so 100b+ 10c + a - (100c + 10b + a) = 90
    90b -90c = 90
    b - c = 1 , (#2)

    case3: interchange 1st and 3rd
    appearance of new number is abc
    value of new number is 100a + 10b + c

    change in value = 100a + 10b + c - (100c + 10b + a)
    = 99a - 99c
    = 99(a-c)

    but if we add #1 and #2
    we get
    a - c = 2

    so 99(a-c) = 99(2) = 198

    A little know feature of the above is the following "math trick"
    1. Pick any 3 digit number, all different and the hundreds digit greater than the unit digit
    2. reverse the digits and subtract the numbers. If you get a 2 digit result, insert a 0 in the hundred place
    3. reverse your subtraction answer and add the last two results,
    4. You will always get 1089

    e.g.

    672
    -276
    -----
    396
    +693
    -----
    1089

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math

    Please help me with the following problem, I have submitted the answer: 88.2 and was told that it was incorrect. The word problem reads: If you do not consider air resistance, gravity causes a falling object to descend a distance of …
  2. Math Middle School

    Please help. I do not have any idea about how to get started on this or finish it. I was told that the answer that I got was not the complete answer that was needed for me to submit. I do not understand how to extend the problem. I …
  3. statistics

    Can someone please tell me how I miss this, I added them up 29 and divided by 8 and came up with 3.625. Below is the question. Please don't send me to other sites and just explain why it is wrong. The number of children, x, belonging …
  4. Math

    Does studying for an exam pay off? The number of hours studied, x, is compared with the exam grade received, y. x 7 7 5 5 7 y 95 90 75 85 95 (a) Complete the preliminary calculations: SS(x), SS(y), and SS(xy). Incorrect: Your answer
  5. math answer check

    x is a binomial random variable. (Give your answers correct to three decimal places.) (a) Calculate the probability of x for: n = 1, x = 0, p = 0.15 P(x) = Changed: Your submitted answer was incorrect. 0.15 x 0 = 0 . (b) Calculate …
  6. math

    Can someone please help me on these I have look at the examples and done just what they did, but I still get it wrong and I only have one more time to try. Use the following table to answer the questions. (Give your answers correct …
  7. math help

    Use the following table to answer the questions. (Give your answers correct to two decimal places.) x 1 1 3 3 5 5 7 7 9 9 y 3 2 6 1 3 3 3 2 5 3 (a) Find the equation of the line of best fit. y hat = + x (ii) Graph this equation on …
  8. MATH

    PLEASE HELP ME UNDERSTAND HOW I WAS TOLD TO USE 1.5 (BEING = TO 50%) * MY NUMBER TO ARRIVE AT THE ANSWER, I WAS PREVIOUSLY MULTIPLYING MY # BY 0.50 AND ACTUALLY ARRIVING AT THE SAME ANSWER AS ABOVE...BUT I JUST NOTICE IN SOME OF THE …
  9. Elementary Satistics

    Test the following function to determine whether it is a probability function. If it is not, then make it into a probability function. (Give your answers correct to one decimal place.) R(x) = 0.2, for x = 0, 1, 2, 3, 4 (a) List the …
  10. math

    The table shows the position of a cyclist. t (seconds) 0 1 2 3 4 5 s (meters) 0 1.4 5.4 10.8 17.4 24.6 (a) Find the average velocity for each time period. (i) [1, 3] 4.45 Incorrect: Your answer is incorrect. m/s (ii) [2, 3] 5.5 Incorrect: …

More Similar Questions