Basis:
1。 Xiaoming has ten trees to plant. How to make tree values into five lines and four lines?
Description: This is a very simple question, but the focus is on the "fun" of the math problem you are interested in.
2.a, B, C, D, four people pass the ball. Where is the ball? Give it to a first. A is thrown to one person (anyone) (but not himself), another person throws it to another person, and then he passes it to another person, and this person passes it to A. Excuse me, how many modes of transmission are there?
Schematic diagram: A-_ _ _ _ _ _-A.
Tip: The second space can be.
Explanation: This question is not very difficult for college students, but a brain-playing problem I saw in the book of Olympic Mathematics.
3. There are four areas, which are painted red, yellow, green, white and black respectively. Adjacent colors cannot be painted.
Schematic diagram: I can't draw it, sorry. For example, the outside is square and the inside is square, and their corners are connected. Draw it, but it's square inside, surrounded by four trapeziums. Have I made myself clear? )
Tip: There are many! Think about it. In addition, every other one can be the same.
Description: This topic is the same as the above type. I don't know, just look at the answer. I have the formula.
4。 There are 1999 pieces, and opponents can catch 1-2 pieces. Whoever catches the last one wins, first or later?
Tip: It is fixed. Fools don't count!
Description: This is a small game type.
Answer:
1。 Draw it like a pentagram. Five rows, four each.
2.3× 1×3+3×2×2=2 1
3。 5×4× 1×3×3+5×4×3×2×2=420
4。 Win first.
I hope my answer is helpful to you! (* _ _ *) Hee hee ...
This is my own hand!