4th Grade math

posted by .

Solve. I have no digits the same. My thousands digit is less than my tens digit. My hundreds digit is twice my ones digit. If you add my digits, the sum would be 25. Who could I be? Could I be 2 numbers?

We can not figure this out. Can someone help please.


Let's find out Marcus
If we have an arbitrary number we use letters. I'm not sure if you're using letters for 4th grade math or not, so correct me if I use methods you don't know yet.

Let the number be denoted by
ABCD Where A is the thousands digit, B is the hundreds digit, C is the tens digit and D is the ones digit.
We're told that
(1) A<>B,A<>C,A<>D,B<>C,B<>D,C<>D
no digits are the same; this <> means 'does not equal'
(2) A < C the thousands digit is less than the tens digit
(3) B = 2*D the hundreds digit is twice the ones digit
(4) A + B + C + D = 25 the digits sum to 25
Using (3) we can eliminate B in (4) to get
A + 2*D + C + D = A + C + 3*D = 25
Now we need to make a simple observation: A + C must have a remaider of 1 when divided by 3. Do see why? It's because 25 has a remainder of 1 if we divide it by 3.
We know A is a number from 1 to 9 and C is a number from 0 to 9.

After testing the numbers that satisfy the requirements I found only two solutions: 6874 and 7693.
I should mentions that you did't state this had to be a 4 digit number. Those are those only ones I checked for.


I thought I would elaborate just a little on how I found the numbers. I didn't have much motivation for this last night.
If you use the letters I gave in the previous post
then we have a number ABCD where A is the thousands digit, B is the hundreds digit, C is the tens digit and D is the ones digit.
Each of the digits goes from 0 to 9 except A which must go from 1 to 8, since it's less than C.
C must go from 2 to 9 because it's greater than A.
B is an even number since B=2*D thus
B= 2,4,6 or 8 it cannot be 0 since D would = 0 too.
Therefore D=1,2,3 or 4 those are the only possible choices.
If D=1, then B=2, but A+C=25-B-D=23
This is impossible since the max for A is 8 and the max for C is 9. Therefore the largest sum of A+C is 17. We can also see that
if D=2, then B=4 and A+C=25-B-D=19 is not possible either.
If D=3, then B=6 and A+C=25-B-D=16
Now run through the numbers where
A<C and A+C=16 A=7 and C=9 is the only possible answer here so 7693 is a solution.
If D=4, then B=8 and 25-B-D=13
Now run through the numbers where
A<C and A+C=13
There are more possibilities here
4+9, 5+8,6+7
We exclude the 4,9 and 5,8 combinations because all the numbers must be different and we've already got a 4 and 8, so 6874 is the only other solution.
Thus the only solutions are 7693 and 6874.
Hopefully you can follow all of the reasoning. I am a little surprised that a problem like this would be given to 4th graders. I suspect that even 8th graders might find this problem just a little challenging.
Hopefully this helps.


Roger, I believe this boy is a 4th grader. He does not understand how you solved this simple problem. It would be better to put it in a language that a 4th grader would understand.


I don't know if he's the 4th grader or not. Sometimes a parent poses these questions too. Also, I'm not entirely sure how or what math is taught to 4th graders. I know they cover fractions, multiplication tables, and other important material, but I'm really quite surprised that this question would be asked at that grade level. Hopefully you're aware that posing even simple questions doesn't mean there are simple answers too. Elementary number theory is filled with questions like this that require college algebra to answer them.
I was doubtful that letters (or variables if you prefer) would be used in problems here, but the explanation will be much longer if I don't use them.
I also hope that if the person posting the question doesn't understand the solution that they'll ask questions. I'll try again if they want me to.


what is name of two astronauts went with Armostrong


they need you to try again and i love you you are sooooooooooooooooooooooooooohot cute and sexy and so cuteer than any boy ever wright back to me lets not talk about school o.k wright back tell me how old you are o.k.

hay!um...can you please help me on this problem?well,anyways what is the answer to this prob.'a plane leaves Miami at 12;12 pm.The flight was supposed to take 1 hour 52 minutes.Was the plane on time?

  • 4th Grade math -

    25

  • 4th Grade math -

    what are variable symbols and what do they stand for

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. 4th grade math

    I'm a 4 digit number with no 2 digits the same. My ones digit is twice my thousands digit and 1 less than my tens digit. My hundreds digit is the difference between my tens digit and my thousands digit. My thousands digit is an odd …
  2. 6th grade

    I have 6 digits. My hundred thousands is less 1 than my ones digits, 8 greater than my thousands digit. twice my tens digit and four times my hundreds digit. My tens digit is 0. what number am I ?
  3. 5th grade math

    i am a number greater than 40,000 and less than 60,000 my ones digit and tens digits are the same. my ten thousands digit is 1 less tha 3 times the sum of my ones digit and tens digit my thousands digit is half my hundred digit, and …
  4. 4th grade

    i am a 5 digit number my tens digit is the sum of my hundreds digit and thousands digit. my tens digit is twice my ones digit.my hundreds digit is 1 more than zero.my thousands digit is seven times my hundreds digit.my ten thousands …
  5. math

    Who am I? I am a 4-digit number wih no two digits the same. My ones digit is twice my thousands digit. My hundreds digit is the diference between my tens and my thousands digit. My thousands digit is an odd number less than 6. I got
  6. math

    find the mystery number, it is a 4 digit odd number, all the digits are different, none of the digits are 0-9, the tens digit is twice the ones digit, and the hundreds digit is twice th tens digit. the thousands digit is one less than …
  7. 4th grade math

    Find the mystery number. It is a 4 digit odd number. All the digits are different. None of the digits are 0 or 9. The tens digit is twice the ones digit, and the hundreds digit is twice the tens digit. The thousands digit is one less …
  8. Math

    Iam a 5digit number my tens digit is the sum of my hundreds digits and thousands digits my tens digit is twice my ones digit. My hundreds digit is 1more than zero.my thousands digit is seven times my hundreds digit.my ten thousands …
  9. math count warm up

    What positive four-digit integer has its thousands and hundreds digits add up to the tens digit. Its hundreds and tens digits add up to its once digit and its tens and ones digits add up to the two digit number formed by the thousands …
  10. math

    I am a 6 digit number between 600 000 and 700 000.My ones digit and tens digit have no values.One of my digits has a value of 600 000.My ten thousands digit is one more than my thousands digit but if both digits are multiplied,the …

More Similar Questions