The sum of the first three digits and the last two digits of a five-digit number is equal to 155: it can be inferred that the first digit is 1.

The sum of the first two digits and the last three digits of this five-digit number is equal to 434: the third digit is 4.

Let this number be 1a4bc.

1a4+bc= 155, which means a *10+b *10+c = 51.

1a+4bc=434, which means a+b* 10+c=24.

Then a=3 b* 10+c=2 1.

b=2 c= 1

So this number is 1342 1.