It is said that three people came to buy melons at the same time, each bought one, and each paid 2 yuan money! Lao Wang received money from 6 yuan, but Lao Wang is a real person. Afterwards, Lao Wang felt that he had overcharged 1 yuan, so he should have collected 5 yuan, so he asked his grandson to return 1 yuan to the three men. The little grandson felt thirsty outside, so he spent 4 cents on a popsicle, so when he found these three people, there was only 6 cents left, so he returned 20 cents to everyone!

Now let's settle the accounts: each of the three people who bought melons spent 2 yuan, and then each person received a refund of 20 cents, which means that each person spent 1.8 yuan's money, and the three people spent * * *: 1.8 * 3 = 5.4 yuan, plus the 4 cents that the little grandson spent on buying popsicles outside, which was only 5.4+0.4=5.8 yuan. ! Where's the rest of 0.2 yuan?

First of all: three people spent * * *: 1.8*3=5.4 yuan, plus my grandson spent 40 cents on popsicles outside, only 5.4+0.4=5.8 yuan! ! . This calculation method is unreasonable, because: 1.8*3=5.4 yuan, this 5.4 yuan is the money spent by three people who bought watermelons, and 0.4 yuan, the grandson who bought popsicles, is part of this 5.4 yuan. This 5.4 plus 0.4 of this 5.4 is meaningless.

In other words, judging from the final result, three people took 5.4 yuan to Lao Wang, Lao Wang took 5 yuan, and the rest of 0.4 yuan was left to his grandson to buy popsicles.

Therefore, the "disappearing 0.2 yuan" mentioned in the question does not exist at all.