Olympiad math test questions and answers in the second grade of primary school.
1. There are two red socks and two black socks in the bag. How many socks can you take out to make a pair of socks with the same color? There are four basketballs and four yellow balls in the schoolbag. How many balls must be found to ensure that two balls of different colors can be taken out at once?
There are four iron balls on each side of the seesaw, so the seesaw keeps balance. If one iron ball is removed, how many iron balls are there on the seesaw?
4. A thread is folded in half and then folded in half, and finally cut from the middle. How many lengths are there in the cut wire?
Kobayashi of Obana made flowers together, and Xiaohua gave her five flowers. They both made the same number of flowers. At this time, Kobayashi has 12 flowers. How many flowers did Xiaohua make?
Reference answer:
1, if you touch two at a time, it happens to be different colors, and then touch 1, it must be the same color as 1. Therefore, at least three socks must be pulled out at a time to ensure that a pair of socks have the same color.
2. If you touch four balls of the same color at a time, you must touch a ball of another color, so you can get two balls of different colors by touching at least five balls at a time.
If an iron ball is removed, there will be no iron ball on the seesaw.
4. Fold it in half and then fold it in half, and cut it in the middle. There are three heads connected, so a * * * has 8-3=5 (segment).
5.A * * * flowers: 12×2=24 (flowers), and florets are 5×2= 10 (flowers) more than Kobayashi.
Method 1: floret: (24+ 10)÷2= 17 (flower) Kobayashi: 17- 10=7 (flower).
Method 2: Kobayashi: (24- 10)÷2=7 (flower) Floret: 7+ 10= 17 (flower).
A: It turns out that Xiaohua made 17 flowers.
Examination Questions and Answers of Olympiad Mathematics in Grade Two of Primary School (Part Two)
Example 1: Xiaoming writes from 1 100. How many numbers did he write "1"? Solution: Classification calculation:
The number of "1" appearing in the cell is:
1, 1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,966.
"1" appears in the tenth digit:
10, 1 1, 12, 13, 14, 15, 16, 17, 18,666.
The number of "1" in the hundreds is:100 * * *1;
* * * 10+ 10+ 1 = 2 1.
Example 2: A picture book is *** 100 pages. When typesetting, a font can only arrange one digit. Please calculate how many fonts are used in the page numbers of this book.
Solution: Classification calculation:
From page 1 to page 9, * * 9, each page uses 1 type, * * uses 1×9=9 (pieces);
From page 10 to page 99, * * 90 pages, each page uses 2 kinds, * * uses 2×90= 180 (pieces);
On page 100, only page 1 * * uses three types, so the total number of types used on page * * * of book 100 is:
9+ 180+3= 192 (pieces).
The third part of the questions and answers of Olympiad Mathematics in the second grade of primary school
1. Sister is 6 years old and brother is 1 1 year old. When brother 16 years old, how old is sister? It takes Xiaoming 25 minutes to walk from school to Children's Palace. If everyone walks at the same speed, how many minutes does it take for Xiaoming, Xiaoli, Xiaogang and Xiaohong to walk from school to the Children's Palace together?
3. 19 The soldiers want to cross the river. There is only one boat. Only four soldiers can sit on the boat at a time. How many times must they cross at least before all the soldiers can cross the river?
4. The power went out at night. Xiaowen lit eight candles at home. First, 1 candle was blown out by the wind, and then two candles were blown out by the wind. How many candles are left at last?
There are 16 children playing hide-and-seek on the playground, and 9 people have been caught. How many people are still hiding?
Reference answer:
1,16-1+6 =11(year)
2. The time for four people to walk from school to Children's Palace is equal to the time for Xiao Ming 1 person to walk from school to Children's Palace, 25 minutes.
3. 19-4= 15 (name) 4- 1=3 (name) 15÷3=5 (times) 5+ 1=6 (times).
4, 1+2=3 (branch)
5, 16-9- 1=6 (person)