A.1225. There was a dog race in the meadow. The German Shepherd, the Rottweiler, the Labrador, and the Cocker Spaniel all ran very fast but still not with the same speed. The German Sheppard ran 320 meters in 20 seconds, the Cocker Spaniel ran 450 meters in three quarters of a minute, the Labrador ran 420 meters in two fifth of a minute, and the Rottweiler ran 1125 meter in one and a half minutes. Which dog is the fastest and what is the order of the rest of them?
A.1226. In a sleep-away camp one morning a few 4th graders took a walk in the forest to enrich their collections. 8 children collected acorns, 7 children collected leaves, and 12 children collected little rocks. Three of them collected all three kinds of items. Every child had a successful morning and found many of the items they liked. What could the smallest and the greatest number of children be on this walk?
A.1227. In the following addition the same letters stand for the same digit, but different letters might not necessarily stand for different digits. What number is the word “DOES”?
A.1228. Using four identical digits and a few mathematical operations, create the number 30 as many different ways as possible.
A.1229. How many rectangles can you see in the following diagram?
A.1230. The sum of the digits of the year 2019 is 12. How many such years were there since the year 1000?
A.1231. a) Move one match stick so that the equality becomes true:
b) Move two match sticks so that the equalities become true:
A.1232. Place parentheses in each of these five expressions so that the equality is true.