In China's classical mythological novel The Journey to the West, it is said that the Tang Priest and his disciples the Monkey King, Pig Bajie and Friar Sand went to the Western Heaven to learn Buddhist scriptures, and in the Lotus Cave in Pingdingshan, the monsters Wang Jinjiao and Wang Yinjiao who wanted to eat Tang Priest's meat were wiped out. Then the disciples went on and met a high and steep mountain. When I was on the road, I looked at the scenery and didn't think it was getting late.

The Journey to the West, written by Wu Cheng'en in Ming Dynasty, has a history of more than 400 years. According to our current mathematical habits, write the numbers in the poem with Arabic numerals and arrange them in a string in turn.

10 9 8 7 6 5 4 3 2 1

Now let's play a math game: use the ten numbers written above, without disturbing the order, and add appropriate mathematical symbols to form ten formulas, so that the calculation results are equal to 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 respectively.

It is easy to form any of these formulas. To form a full set of ten, you have to use your head. It would be more interesting if the composition of the ten formulas were changed again.

There are many formulas that meet the requirements, and the following is one of them.

10+9-8-7+6+5-4-3+2× 1= 10;

( 10+98+76)×5÷4÷(3+2)+ 1=9;

( 10+9+8-7)×6÷5÷4+3-2+ 1=8;

( 109-87)÷(6+5)+4+3-2× 1=7;

( 10+9+8-7-6)×5-43-2 1=6;

( 10+9+8+7+6)÷5-4÷(3-2)+ 1=5;

10×9-87+65-43-2 1=4;

( 109-8+7)÷6-54÷3+2+ 1=3;

( 109+87-6)÷5-4-32× 1=2;

( 10×9-87)÷(6×54-32 1)= 1。

The story develops here, and the novel writes:

..... Master and apprentice were playing with the mountain scenery, believing it, and walking without realizing that the red wheel was setting in the west. To be exact:

There are no guests walking in the Shili Pavilion, and there are stars in the sky.

All ships in Bahe River are closed, and all seven thousand counties are closed.

Six palaces and five houses belong to the official slaughter, and the four seas and three rivers fish.

The bell rang on the second floor, and a bright moon filled Kun.

This poem ranges from ten, nine, eight, seven to six, five, four, three, two and one. The stars and the moon decorate the night. It's time to call it a day. After work, it's closed and there's no one on the road. It's time for those who are on their way to learn the scriptures to find a place to rest.

In order to learn from the scriptures, it is already very miserable to wade through mountains and rivers, and it is even more dangerous to subdue demons, which makes Pig Bajie want to go home, and Tang Priest is also playing drums in his heart. Fortunately, the Monkey King kept encouraging this group of people to see the quiet scenery in the mountains along the way and relax. This landscape poem in the novel is just a little light tidbit in a tense plot, which makes people catch their breath. All ten numbers are embedded in the poem, and the countdown from big to small becomes a unique "countdown poem", which adds more interest.