Question 101
a four-digit number $a b c d$ It is called balanced if
$$
a+b=c+d
$$
Calculate the following quantities:
a) how many numbers $a b c d$ are such that $a+b=c+d=8$ ?
b) how many numbers $a b c d$ are such that $a+b=c+d=16$ ?
c) How many balanced numbers are there?
$$
a+b=c+d
$$
Calculate the following quantities:
a) how many numbers $a b c d$ are such that $a+b=c+d=8$ ?
b) how many numbers $a b c d$ are such that $a+b=c+d=16$ ?
c) How many balanced numbers are there?