Question

There is an unknown number •it is a four digit number •the tens are double the ones •the thousands are double the tens •the sum of the digits of nineteen

Answer 1

8542

Statement

1.It is a four digit number

2.The tens are double the ones

3.The thousands are double the tens

4.The sum of the digits is nineteen

Explanation:

It is a four digit number

lets take 4 digit number-ABCD

The tens are double the ones

`C=2D`-----------------------------1

The thousands are double the tens

`A=2C`-------------------------------2

According to equation 1 and 2

`A=4D`

If we take

`D=1,2`

Possible number

`4B21` OR
`8B42`

The sum of the digits is nineteen

I use hit and trial method

`4B21`- If I take B is maximum

`4+9+2+1\\eq 19`

`8B42`- If, i try to find value of B

`8+B+4+2=19`---------------------3

`14+B=19\\B=19-14\\B=5`

So the unknown number is- 8542