Question

A number is totally even if all its digits are even. For instance, the numbers 2022 is totally even. How many four-digit totally even numbers X are there such that X + 2022 is totally even?

Answer 1

The units digit of our number should be and can be any of 0, 2, 4, 6 (four opportunities).

The tens digit of our number should be and can be any of 0, 2, 4, 6 (four opportunities).

The hundreds digit of our number should be and can be any of 0, 2, 4, 6, 8 (five opportunities).

The thousands digit of our number should be and can be any of 2, 4, 6 (three opportunities).

So, there are 4*4*5*3 = 16*15 = 240 such 4-digits totally even numbers, satisfying the condition. ANSWER

Explanation: