Question

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 and hundreds digits?

Answer is 1459 wanted to know how this is arrived ?

Answer 1

just start writing down the facts. If the 4 digits, left to right are a,b,c,d, then:

a+b=c
b+c=d
c+d=10a+b

a+b=c
d-b=c
10a+b-d=c

a+b=d-b
a+2b = d

10a+b-(a+2b) = a+b
8a = 2b
b = 4a
so, c=5a
and, d=9a

Since a,b,c,d are single digits, a must be 1. So, we get

1459

Answer 2

i still don't get it