Math, asked by khwaiskhhh, 10 months ago

can you find the next no. having this property​

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Answered by Prakhar2708
1
Here is your answer my friend—
The next number might be the double of 59 that is 118.
When 118 is divided by:
6, the remainder is 4.
5, the remainder is 3.
4, the remainder is 2.
3, the remainder is 1.



Hope it helps........
Please mark me as the brainliest!!!!!
Answered by shadowsabers03
5

So the number 59 has a property as mentioned in the question. These are due to the facts that,

  • 59 - 1 = 58 is exactly divisible by 2.
  • 59 - 2 = 57 is exactly divisible by 3.
  • 59 - 3 = 56 is exactly divisible by 4.
  • 59 - 4 = 55 is exactly divisible by 5.
  • 59 - 5 = 54 is exactly divisible by 6.

Let us have a number 10a+b, where b is strictly a 1 - digit number and a is not strictly a 1 - digit number, can be of two or more, which can be written decimally as a/b, such that,

  • a/(b-1) is exactly divisible by 2.
  • a/(b-2) is exactly divisible by 3.
  • a/(b-3) is exactly divisible by 4.
  • a/(b-4) is exactly divisible by 5.
  • a/(b-5) is exactly divisible by 6.

[Note:- Writing decimally means to write a number by splitting its digits by some symbols (here I used / which is not used for division.)]

Since a/(b-4) is exactly divisible by 5, the ones digit, i.e., b-4, must be either 0 or 5.

\textit{``Multiples of $5$ either ends in $0$ or in $5$."}

Since the numbers a/(b-3) and a/(b-5) are exactly divisible by 4 and 6 respectively, they should be even, thereby implying that a/(b-4) should be odd.

Therefore, a/(b-4) ends in 5.

\longrightarrow\sf{b-4=5}

\longrightarrow\sf{b=9}

Hence our number is in the form a/9, such that,

  • a/8 is exactly divisible by 2.      
  • a/7 is exactly divisible by 3.
  • a/6 is exactly divisible by 4.
  • a/5 is exactly divisible by 5.
  • a/4 is exactly divisible by 6.

Since a/6 is exactly divisible by 4, 'a' should be an odd number.

\textit{``Tens digit of multiples of $4$ ending in either $2$ or $6$ is always odd."}

Tens digit of a/6 is the same as ones digit of 'a'. Since it is odd, so is 'a'. Let,

\longrightarrow\sf{a=2x+1\quad\quad\dots(1)}

for \sf{x\in\mathbb{W}.}

Since a/7 is exactly divisible by 3, sum of digits of 'a' added to 7 should be exactly divisible by 3.

Let sum of digits of 'a' be \sf{S(a).} The sum of digits of a/7 will be \sf{S(a)+7.}

For a/7 being exactly divisible by 3,

\longrightarrow\sf{S(a)+7\equiv0\pmod{3}}

Since \sf{7\equiv1\pmod3,}

\longrightarrow\sf{S(a)+1\equiv0\pmod{3}}

\longrightarrow\sf{S(a)\equiv-1\pmod{3}}

Since \sf{S(a)\equiv a\pmod{3},}

\longrightarrow\sf{a\equiv-1\pmod{3}}

Then let,

\longrightarrow\sf{a=3y-1\quad\quad\dots(2)}

for \sf{y\in\mathbb{N}.}

From (1) and (2),

\longrightarrow\sf{2x+1=3y-1}

\longrightarrow\sf{3y=2x+2}

\longrightarrow\sf{3y=2(x+1)}

\Longrightarrow\sf{2\,\mid\,3y}

Since 2 is relatively prime to 3,

\Longrightarrow\sf{2\,\mid\,y}

Now we've to assume possible values for \sf{n} to get possible numbers satisfying the property.

Let \sf{y=2.} Then,

\longrightarrow\sf{a=3\times2-1}

\longrightarrow\sf{a=5}

Therefore,

\longrightarrow\sf{a/9=59.}

This is already described in the question.

Let \sf{y=4.} Then,

\longrightarrow\sf{a=3\times4-1}

\longrightarrow\sf{a=11}

Therefore,

\longrightarrow\sf{\underline{\underline{a/9=119}}}

Thus 119 has the same property.

Let me find next possible number. Let \sf{y=6.} Then,

\longrightarrow\sf{a=3\times6-1}

\longrightarrow\sf{a=17}

Therefore,

\longrightarrow\sf{a/9=179}

Thus 179 also has the same property.

Finally, let me find the general form of such numbers having the property.

For this we have to write a/9, written decimally, in general form as,

\longrightarrow\sf{a/9=10a+9}

From (2),

\longrightarrow\sf{a/9=10(3y-1)+9}

Since \sf{2\,\mid\,y,} let \sf{y=2n,\quad n\in\mathbb{N}.} Then,

\longrightarrow\sf{a/9=10(3(2n)-1)+9}

\longrightarrow\sf{a/9=10(6n-1)+9}

\longrightarrow\sf{a/9=60n-10+9}

\longrightarrow\sf{\underline{\underline{a/9=60n-1}}}

Therefore, numbers in the form \sf{60n-1\quad\!\forall\,n\in\mathbb{N}} have the property mentioned in the question.

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