A secret lair has a code to only allow members to enter. The person wanting to enter says a random number, then is told a number in response. In order to enter they must say the correct third number. Here are sequences that allowed entrance.
Five because s-e-v-e-n has 5 letters. The first number can be anything, the second number is the number of letters in the first number, and the third number is the number of letters in the second number.
Joe and Andrea want to copy three 60-minute cassette tapes. They have a 2-cassette recorder to copy the tapes, allowing them to copy two tapes at a time. Each side takes 30 minutes to be copied, so two tapes can be copied in an hour and the third will take another hour. Andrea bets Joe she can copy all three tapes in 90 minutes. Does she win the bet?
In the first 30 minutes Andrea copies the A sides of tape 1 and 2.
In the second 30 minutes, she copies tape 1 side B and tape 3 side A (finishing Tape 1).
In the last 30 minutes, she copies tape 2 side B and tape 3 side B.
Hans made a meandering journey from Paris to Roye. On the first day, he went half of the distance. On the second day, he went one third of the remaining distance. On the third day he went three quarters of the remaining distance. The next day he traveled half of the remaining distance and was left with 5 kilometers to get to Roye. How far was the entire journey?