Sam has four of each of 1-dollar, 2-dollar and 10-dollar coins respectively and two 20-dollar notes. He buys a 45-dollar piece of clothing. How many different payment methods require no change?
Peter saves his pocket money by saving 1 dollar every Monday; 2 dollars every Tuesday; 3 dollars every Wednesday; ...; 7 dollars every Sunday. He started saving on Friday, August 1st. How much has he saved this month?
There are 150 number cards in a bag, with 001–150 written on them. In the worst case, at most how many cards will be drawn and still no card with the digit “0” on it?
The well is 12 meters deep. The snail climbs up 4 meters during the day and slides down 2 meters at night. In how many days will the snail reach the wellhead?
This year, the elder brother is 12 years old and the younger brother is 7 years old. How old will each brother be when the sum of their ages is 35? Show your reasoning.
Printed scoring note: each Part III question is worth 10 points; a simplified solution is required and is worth 4 of those points.
The elder sister and the younger sister played “rock-paper-scissors” three times. Each win moves them up 2 stairs; each loss moves them down 1 stair. They both started on the 5th stair. Finally, the elder sister won 2 times and the younger sister won 1 time.
(a) How many steps apart were they at the end of the game?
(b) On which step were the two sisters respectively? Show your reasoning.
Printed scoring note: each Part III question is worth 10 points; a simplified solution is required and is worth 4 of those points.