How many 4-digit numbers can be formed by 123456 without repetition and divisible by 3?

How many 4-digit numbers can be formed by 123456 without repetition and divisible by 3?


Let's see which four digits of 123456 can be divided by three
There are 1 + 2 + 3 + 6 = 12; 1 + 2 + 4 + 5 = 12; 1 + 3 + 5 + 6 = 15; 2 + 3 + 4 + 6 = 15; 3 + 4 + 5 + 6 = 18; so there are five groups of numbers that meet the above requirements
Taking 1, 2, 3 and 6 as examples, 4 * 3 * 2 = 24 four digit numbers without repetition and divisible by 3. Therefore, 24 * 5 = 120 can be formed in total