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Xiao Ming read a story book. On the first day, he read one fifth of the whole book. On the second day, he read 121 pages. There is still a quarter left. How many pages is there in this book? I'm so anxious. I don't have to add 20 points to my score
121÷（1-1/5-1/4）=220
Manager Li's driver gets home at 7:30 every morning to pick him up for work at the company. One day, manager Li leaves home at 7:00 and walks to the company. On the way, he meets a car that comes to pick him up on time and takes a bus to the company. As a result, he arrives 5 minutes earlier. When did manager Li meet the car? How many times the speed of a car is that of a walk?
Manager Li is early: 7:30-7:00 = 30 (minutes) one way car saving time: 5 △ 2 = 2.5 (minutes) when meeting, manager Li left: 30-2.5 = 27.5 (minutes) 27.5 = 27:30, 7:00 + 27:30 = 7:27, 27:30, speed is walking: 27.5 △ 2.5 = 11 A: when manager Li meets a car at 7:27, 27:30, speed is 11 times of walking speed
From the largest three digits to the largest five digits, how many of these numbers are made up of the same number?
If you can understand it, don't make equations,
999 to 99999 if these two numbers are included, there are 19
3 digits: 999
Four digits: 1111, 2222, 3333, etc
5 digits: 11111, 22222, 9999, etc
999-99999；
1111,2222,3333,4444,5555，。。。 9999, 9 in total;
1111122222,..., 99999; 9 in total;
Total number = 9 + 9 + 1 = 19
Xiao Ming read a story book. On the first day, he read 3 / 8 of the total pages. On the second day, he read 2 more pages than on the first day. There are still 20 pages left. How many pages are there in this book?
Suppose the book has x pages
There is an equation according to the meaning of the question
3/8x+3/8x+2+20=x
1/4x=22
x=88
For a project, team a needs 12 days to complete it alone. If team a and team B work together for 5 days, the rest of the project will be completed by team a alone, and it will take another 3 days. How many days does team B need to complete it alone
Work efficiency of team B: (1-112 × 3) △ 5 − 112 = 34 △ 5 − 112 = 320 − 112 = 115 time required for team B to do it alone: 1 △ 115 = 15 (days) a: it takes 15 days for team B to do it alone
Use 1, 2, 3, 4 and 5 to form a two digit number and a three digit number? What about minimizing the product? Try five more numbers?
According to the nature of multiplication and digital knowledge, 5 ＞ 4 ＞ 3 ＞ 2 ＞ 1, so use 1, 2, 3, 4, 5 to form a three digit multiplication of two digits, to make the maximum product should be: 431 × 52 = 22412; to make the minimum product should be: 13 × 245 = 3185
Xiao Ming read a 120 page story book. He read 40% of the whole book on the first day and 25% on the second day. How many days are left?
It's not how many days are left. It should be how many pages are left
120 × (1-40% - 25%) = 120 × 35% = 42 (page)
Be sure to calculate by proportion!
The distance between a and B is 300 kilometers. A car runs 120 kilometers in 1.2 hours. At this speed, how many hours does it take for the car to go from a to B? (calculated in proportion)!
Suppose it takes x hours for the car to go from place a to place B
1.2：120=X：300
120X=360
X=3
It takes three hours for the car to go from place a to place B
300:120=x:1.2
So x = 3 hours
The distance ratio is equal to the time ratio
Use 1, 2, 3, 4 and 5 to form a two digit number and a three digit number? What about minimizing the product? Try five more numbers?
According to the nature of multiplication and digital knowledge, 5 ＞ 4 ＞ 3 ＞ 2 ＞ 1, so use 1, 2, 3, 4, 5 to form a three digit multiplication of two digits, to make the maximum product should be: 431 × 52 = 22412; to make the minimum product should be: 13 × 245 = 3185
A story book has 120 pages. Xiao Ming read 20% of the whole book on the first day and a quarter of it on the second day. How much is left
120 × 20% = 24 (pages)
120 × 4 / 1 = 30 (page)
120 - (24 + 30) = 66 (page)
A: there are 66 pages left to read
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