= 12 1×(30+42+56+72)
=24200
2, the original formula =+= 0.466557 or multiply.
0. 12 12 12 12 12 12 ……
+0.34545345 ... You can see that the loop segment is 466557.
0.466557466557 ……
3、① 18 1-42×4= 13 42- 13=29
② 42×5- 18 1=29 42-29= 13
The quotient of 4,72 ÷ 24 = 3,68 ÷ 24 = 2 ... 20 is three times that of the original, and the remainder is 20.
5.(44÷2+6×2)÷2 = 17cm 17- 12 = 5cm 17×5 = 85cm。
6. Brother: (5+5) ÷ (2- 1) = 10 years old Brother: 10+5 = 15 years old.
7. 18÷9× 12=24 square centimeters Divide one of the regular triangles into small triangles, and it is relatively simple to calculate the number of copies.
8. Move 5 pieces at a time, * * * move 54÷5= 10 times. There are still four blocks on the square A. Move it again, and the square A will become the bottom one, so * * move10+1=1times.
9. Triangle: 20 isosceles triangle: 6 equilateral triangle: 2.
10, sports, literature and art, science and technology activities are A, B, C,
The first day can be a, b, c, let's assume that the first day is a, and the rest days are fine.
It can be found that neither the first nor the sixth arrangement can guarantee all kinds of activities under one arrangement at least once, which is not acceptable. * * * There are six arrangements that meet the requirements. Similarly, there are six arrangements of B or C on the first day, ***6×3= 18.
1 1, the original formula = 0.0 ... 01×10 ... 0 = 0.01.
12, the number is 75.
13. The four cards are hearts A, spades A, diamonds A and clubs A from left to right.
14、3000-3=2997 ( 14593+2997)÷2=8795
15, 2000÷25=80, 2000÷320=6.25, 80+ 1.25-6.25 = 75.
16, the sum of internal angles in the middle part of the five-pointed star is 180× 3 = 540, and each internal angle is 540 ÷ 5 = 108, and its angle on a straight angle is180-108.
17,43.32-14.07 = 29.25 yuan: 29.25 ÷ (1-0.1) = 32.5 yuan.
Another piece: 43.32-32.5 = 10.82 yuan.
18, (88-74) ÷ (76-74) = 7 people 74× 6-70× 5 = 94.
19, ① [2.3]=6, just set the whole journey as a multiple of 6 meters, and set the whole journey as 6 meters.
From the beginning to the first meeting, it takes 6 ÷ (6 ÷ 3+6 ÷ 2) = 1.2 points.
From the first meeting to the second meeting, one * * *: requires two whole runs: (6× 2) ÷ (3+2) = 2.4 points.
* * * Meetings: (30-1.2) ÷ 2.4+1=13 times.
② [2.3]=6, 30÷6=5. They met three times in the first six minutes and twice in the last six minutes, and so on, with 3+2+3+2+3 = 13 times.
20,24.78 is between 24.7 and 24.8, while 24.8× 12=297.6 years old and 24.7× 12=296.4 years old. Because the total age of several players must be an integer, and the integer between 297.6 and 296.4 is only 297, so the total age is 297.
Average age: 29712 = 24.75 years old.
2 1, 1 1.2× [( 1 1.2× 0.5-2) ÷ ( 12. 1- 1 1.2).
22. First time: 6 o'clock.
The second time: 10: 48 When we met for the second time, people and cars walked two whole distances together.
60× 2 ÷ (20+5) =4.8 hours 4.8 hours = 4: 48.
4: 48+6: 00 = 10: 48.
The third time: 14: 00 When we met for the third time, the car caught up with someone. Catch-up distance ÷ speed difference = catch-up time
5× 4.8× 2 ÷ (20-5) =3.2 hours =3 hours 12 minutes.
10: 48+3: 00: 12: 14: 00
Fourth time: 15: 36
60× 4 ÷ (20+5) =9.6 hours = 9.6 hours, 6: 00+9: 36 = 15: 36.
The fourth time I saw a police car passing by him, the man and the car walked four times together. )
23,26 decimetres
24, 2 o'clock sharp1996 ÷12 =166 laps ... four o'clock direction.
25, at least need 13 points. It takes 2 points for A and B to cross the river for the first time, 1 point for Xiaoming to ride back and 3 points for * * *. It takes 6 points for C and D to cross the river for the second time, 2 points for Xiaoming to ride B and 8 points for * * *. For the third time, it takes 2 points to cross the river, so * * 3+8+2 = 13 points.
26、 1995- 1+(9+9)÷6= 1997 1+2+34×56+7-8+90= 1996
27.( 1) The original formula =1997× 2000×10001-2000×100065438.
(2) The original formula =1+(3-2)+(5-4)+...+(1995-1994)+1996.
= 1+997+ 1996
=2994
28. Let the point on AB be E, the angle DEC be a right angle (this is a known condition, and the figure on the topic is omitted), and AD=AE CB=EB.
Ad+CB = AE+EB = 22cm 22x22÷2 = 242cm2。
29、① (5+5)×(3+3)÷2-5×3÷2=22.5
② Divide the shadow into three equal parts, so that each part is equal to a blank small right triangle. 5×3÷2×3=22.5
30. The score of ①16 ÷ 2× (35-15) ÷ 50 = 3.2 decreased by 3.2 points.
② The average score of the last 15 can be set as X, and the average score of the top 35 is X+ 16.
The correct calculation method is: [35 (x+16)+15x] ÷ 50.
=[35x+560+ 15x]÷50
=x+ 1 1.2
The wrong calculation method is: (x+x+ 16) ÷ 2 = x+8.
So: (x+11.2)-(x+8) =11.2-8 = 3.2 (point).
3 1, 20.6 ÷ 4+20.6 ÷10-3.95 = 3.26 hours.
Xiao Li walked two full distances, of which the uphill journey when he went and the uphill journey when he came back was 20.6 kilometers, and the downhill journey was also 20.6 kilometers.