Math diary, a fifth-grade student, see if it works. 65438+1October 3 1 Sunday Sunny Today, my father gave me a task to estimate how many people live in Chen Kai community. How can I finish this task? You can't let me count them one by one, can you? I've been thinking about it for a long time. If I could know how many houses there are in Chen Kai community, how many families there are in each house and how many people there are in each family, I would come out! How do I know how many houses there are in Chen Kai community? As I remember, there was a map showing the distribution of communities in Chen Kai. I'll go downstairs and find the distribution map right away. I see that the biggest house number on the distribution map is 16 1. But not all buildings have the height of 16 1, including villas, small high-rise buildings and multi-storey apartments. There are three buildings 165438+. There are 10 villas with 1 house numbers respectively. The rest are all six-story multi-storey apartments. What's the number of the multi-storey apartment? It should be calculated as follows:161-3× 2-10×1=145. Knowing the house number and the number of floors, I can calculate the number of households, but how many people does each household count? I assume that there are three people in each household. Total number of villas = 10× 3 = 30 people; The total number of people in small and high floors = 3× 2×11× 2× 3 = 396; Total number of people in multi-storey apartment: 145× 6× 2× 3 = 5220. So the total number of people in the community is about 30+396+5220 = 5646. After finishing my father's task, I feel very happy and I feel quite capable. It is not easy to count the number of people living in this community. Class 5 (4) XXX 666. My parents took me to buy stationery. When I arrived at Qilu Stationery Store, I saw all kinds of book covers, including Miss Rabbit's, Pleasant Goat's and Big Big Wolf's, and Blue Bear's ... I saw the price list: 5.00 yuan for small book covers and 6.00 yuan for large book covers, so I immediately took 5 small book covers and 4 large book covers. Walking, I saw a beautiful pencil case. "Just the last one!" I pleaded. "Well, it's the last one!" "hmm!" With that, I picked up the pencil case I chose and put it in the basket. When I got to the cashier, my father said, "You calculate first. How much do these cost?" I counted: "5×5+6×4+6, hmm. 25+24+6=55 yuan! " Mother handed 55 yuan to the shop assistant, and our family went home happily.