Who give me a few elementary school fifth grade (Volume I) mathematics problems! no It's a little harder

Who give me a few elementary school fifth grade (Volume I) mathematics problems! no It's a little harder

1. 90 trees can be protected by recycling 5 tons of waste paper, and how many trees can be protected by recycling 54.5 tons of waste paper?
2. It's 7.2km from the bottom of the mountain to the top of the mountain. It took Xiaoming three hours to go up the mountain and two hours to go down the mountain. How fast is the speed of going down the mountain faster than that of going up the mountain?
3. Granny Wang saved 34.5 yuan in the first half of the year, and Granny Li saved 21 yuan in the second quarter. Who saved more water each month? How much more?
4. 10000 square meters of forest can absorb 6.3 tons of carbon dioxide per week. Now there are 50000 square meters of forest. How many tons of carbon dioxide can be absorbed in February 2008?
5. My mother is 36 years old, 4 times less than Xiao Ming's age. How old is Xiao Ming?
6. One cycle of the earth around the sun is 365 days, 13 days more than that of mercury. How many days does mercury around the sun take?
7. Each carton can hold 15 kg of fruit at most. Now there are 680 kg of fruit. How many cartons do you need?
8. It's 7.2km from the bottom of the mountain to the top of the mountain. It took Xiaoming three hours to go up the mountain and two hours to go down the mountain. What's his average speed?
9. There is a 25m long packing tape. Each gift box needs to be 1.5m long. It can pack several gift boxes at most
10. The area of the Forbidden City is 720000 square meters, 160000 square meters less than twice the area of Tiananmen Square. How many square meters is the area of Tiananmen Square?

In a swimming competition, Ding Ding swims 28 meters in 30 seconds, Xin Xin swims 23 meters in 25 seconds and Ning Ning swims 19 meters in 20 seconds, (2) in the group of 1.67, 7 / 5, 1.3 and 170%, the largest number is (), and the smallest number is (). (3) a glass of milk, half of which is filled with water, and half of which is filled with water. This is the ratio of milk to water in the glass. Fill in the same book in (), Make the equation hold. (x = multiplied by) 24 × () + () × 16 = 18 () - 0.72 × () = 56 6.2 × () - () = 4.16 () × 13.2 + 1.8 × () = 66.64 write directly the number 0 / 6 / 17 = 1 / 3 × 30%=

Dingding: 14 / 15 (M / s) Xinxin: 23 / 25 (M / s) Ningning: 19 / 20 (M / s) 23 / 25

Fifth grade mathematics holiday life (Hebei Education Press)
The floor of a flat room is a square. Now you need to lay floor tiles. Whether you choose a square floor tile with a side length of 50cm or a square floor tile with a side length of 60cm, it's just full. How many square meters is the floor of a flat room at least?

Answer: 9 square meters two ideas: 1, from the room side length to think: 50cm, 60cm can be covered, indicating that the side length is just the common multiple of 50 and 60, the question asked at least, then the minimum common multiple of 50 and 60 is 300, indicating that the side length of the room meeting the conditions is at least 300cm, that is, 3M, then the area is 9 square meters