20 interesting maths

Question 1: Xiaogang's house is in an alley. A classmate asked him his house number. Xiao Gangbing said: "If my house is number X, then add up all the house numbers in the alley except my house and subtract them, which is exactly equal to 100. Moreover, the house number of our alley starts with 1, and there is neither a jump number nor a jump number. Please calculate, Xiaogang's house number is:. Question 2: Mr. Zhang looked at his watch at the beginning of the school freshman party. At the end of the party, he looked at his watch again and found that the minute hand and the hour hand had just exchanged places. The party starts from 6: 00 to 7: 00 and ends at 9: 00/kloc-0. Please calculate that the start and end times of the party are and respectively. Question 3: Teacher Liu drew six dots on the blackboard. No matter which three points you choose to form a triangle, it is an isosceles triangle. How are these six points placed? Please draw it. Question 4: Xiao Gang, Xiao Qiang and Xiao Long played table tennis with three female students at the same table, and held mixed doubles for men and women, agreeing not to be deskmate partners. In the first set, Xiaogang and Xiaoying played against Xiaolong and Xiaoling; In the second group, Xiaolong and Xiaohong sit at the same table with Xiaogang and Xiao Qiang. Please guess whose deskmate Xiaoying, Xiaohong and Xiaoling are: 1, 10 2, starting time 6: 47.83, ending time 9: 33.99 3, points 2, 3, 4, 5 and 6 are located at the five vertices of the regular Pentagon, and point 1 is located at the regular Pentagon. 4. Xiaoying's deskmate is Xiaolong; Xiaohong's deskmate is Xiaogang; Xiaoling's deskmate is Xiao Qiang. Solution: Suppose there are n hutongs where Xiaogang lives, and the house number of Xiaogang's house is X. From the meaning of the question, both N and X are integers, so when n= 15, x= 10 meets the requirements. Verification:1+2+3+4+5+6+7+8+9+1+12+13+14+/kloc-0.