Explain what is wrong and why it is wrong.?

He will need to buy more clothes. In order to figure out the possible combinations, multiply all 3 together to get 360.

Since 360 < 365, he will need more clothes to go to work every day in a different outfit.

There are 3*10*12=360 combinations of outfits. There are 365 days in a year. That assumes John works every day of the year. Most people work 5 days a week. That means he only shows up to work 5/7*365=261 days a year, which means he does have enough combinations.

of different outfits = 3 * 10 * 12 = 360

So if John come to work more than 360 day a year (how likely is that???), he seemingly needs more clothes.

BUT if he chooses to make an outfit without a necktie, then we get

# of different outfits = 3 * 10 * 13 = 390

which is more than enough to get a different outfit each day