Grades 7-8 Video Solutions 2021-video 2021 7-8/9

Video Transcription

Question 9. A bike lock has four wheels numbered with the digits 0 to 9 in order. Each of the four wheels is rotated by 180 degrees from the code shown in the  first diagram to get the correct code. What is the correct code for the bike lock? First we have to recognize that if we look at each of the single wheels  from a side, it is a decagon, meaning it is a shape with 10 sides which are numbered from 0 to 9. We know we need to turn it 180 degrees, which means that it  will be flipped completely from one side to the other, for example from 2 to 7. So we know to turn 180 degrees we have to add 5 or subtract 5. So looking at the  numbers we have, 6, 3, 4, and 8, we just have to add or subtract 5 to get the result that would be on the other side. And then when we do that we get 1, 8, 9, 3.  And we can see that this is one of the solutions, B, 1893.

Video Summary

Question 9. A bike lock has four wheels numbered with the digits 0 to 9 in order. Each of the four wheels is rotated by 180 degrees from the code shown in the first diagram to get the correct code. What is the correct code for the bike lock? First we have to recognize that if we look at each of the single wheels from a side, it is a decagon, meaning it is a shape with 10 sides which are numbered from 0 to 9. We know we need to turn it 180 degrees, which means that it will be flipped completely from one side to the other, for example from 2 to 7. So we know to turn 180 degrees we have to add 5 or subtract 5. So looking at the numbers we have, 6, 3, 4, and 8, we just have to add or subtract 5 to get the result that would be on the other side. And then when we do that we get 1, 8, 9, 3. And we can see that this is one of the solutions, B, 1893.

Keywords

bike lock

decagon

180 degrees

code

solution