1. The original formula =(70+90)÷4÷4= 10.

2. The original formula =1000+10000+100000-102× 4 =16550.

3. The original formula =(2×3+3)⊙(2×4-2)=9⊙6=9×6+6=60.

4.97 is even, so the original number is even. Because it is divisible by 5, the single digit is 0. The decimal number is not less than 6, which may be 60, 70, 80, 90, of which only 70 is not divisible by 3 or 4.

5. First, it is observed that the first lines are 2, 4, 6 and 8. According to the first column and the third column, the equivalent quotient is 3, so the table can be deduced as follows:

2 4 6 8

6 12 18 24

18 36 54 72

54 108 162 2 16

a+b×c= 108+72×6=540 .

6. The difference between its cubic and 4 is a multiple of 10, that is, its cubic unit number is 4 and its original unit number is 8. The difference between its quadruple and 15 is between 60 and 100, that is to say, its quadruple is between 75 and 1 15, and its primitive number is between 19 and 28, so its primitive number is 28.

7. There are four methods in a thousand, one in a hundred 1 method, five in ten, and five in the company, so there are 4× 1×5×5= 100.

8. Obviously, only four isosceles right-angled triangles with a right angle of 6 can be cut at most, so the area of the remaining part is 12×8-2×6×6=24 square centimeters.

9. If the divisor is 9 to 6, the remainder is 1 4; If the divisor is less than or equal to 5, the remainder is at most 4. So the sum of the remainder is 0+ 1+2+3+4= 10.

10. There are 7 apples and 3 pears in each bag. If you want to pack all the pears, you need 12÷3×7=28 apples. So the difference between the two methods is 4+28=32 apples, and * * has a group of 32÷(7-5)= 16, so * * has 16×3=48 pears, 16×5+4=84 apples.

1 1. There are six basic triangles, three triangles are composed of two basic triangles, and six triangles are composed of three basic triangles and a big triangle, so * * * has 6+3+6+ 1= 16. There are four different values because the areas of basic triangles are all equal.

12. Discuss in two situations:

The first type: A and B, A, C and D, B, A and B, * * * needs 4+3+6+4 = 2 1 min;

The second type: A and B, A, A and C, A, A and D, * * * takes 4+3+5+3+6=2 1 min.

Therefore, at least 2 1 min is needed.

13. The speed ratio of motorcycle and automobile is 120: 180=2:3, so the answer is 2×2÷(3-2)=4 hours, and the second condition is redundant.

14. Let the sum of three numbers be 3a, 3a and a respectively, and the middle number be x, then the sum of seven numbers plus 2x equals 7a, that is to say 2x+ 132=7a. 2x+ 132 is a multiple of 7, which means that x+66 is a multiple of 7, and x divided by 7 is 4. There are 1 1 and 18 divided by 7 and 4, corresponding to 22 and 24. After testing, the former can and the latter can't.

15. The total number of people who answered incorrectly is 7+10+14+9+20+17+28+25+22+41=193, each person. To illustrate that this is possible, please note that 4 1 is just 3 more than 38, so 38 people got the wrong answer on the question 10, and the rest of the wrong answers were just evenly distributed among the other 9 questions:

The title is 1 23455 6789 10.

All pairs 59 59 59 59 59 59 59 59 59 59 59 59 59 59 59 59 59 59 59 59 59

Only the last question is wrong, 3333333.

A loser

9 9 9 9 9

4 4 4 4 4

3 3 3 3 3

1 1 1 1 1

1 1 1 1 1

Total *** 93 90 86 9 1 80 83 72 75 78 59

16.B If you want to see A, you must be in the same "slot". A climbs an edge every 4 seconds, and B climbs an edge every 5 seconds.

A's time period b's time period b can see a's time.

First groove 0 sec ~4 sec 0 sec ~ 10 sec 4 sec

The second slot is 4 seconds ~ 12 seconds 10 seconds ~20 seconds.

The third tank 12 sec ~20 sec ~ 20 sec ~30 sec 0 sec

The fourth slot is 20 seconds to 28 seconds, 30 seconds to 40 seconds, and 0 seconds.

The fifth slot is 28 seconds to 36 seconds, 40 seconds to 50 seconds and 0 seconds.

So the time for B to see A is 4+2=6 seconds.