ABACUS International Math Challenge
for
3rd and 4th graders
December, 2001
A.281. Help Numby Math to put the following
numbers into three groups so that every group has the same number of numbers,
and the sum of the numbers in each group is the same!
6, 1, 3, 5, 2, 7, 8, 4, 9
A.282. Using all of the following digits,
create two 3-digit numbers with the
a) greatest sum
b) smallest difference.
0, 1, 2, 3, 5, 9
A.283. "I like your belt!" -
says 0 to 8. "I would like to be next to you all the time!"
How many times does this happen in the numbers from 1 to 1000?
A.284. Romeo takes a walk every 5th day,
and Julia takes a walk every 7th day in the park hoping that they meet.
On the day of Christmas they almost met because Romeo was in the park on
December 24, and Julia was there on December 25. When are they going to
meet next time?
A.285. Gabe and Cynthia are playing a math
game. Gabe picked five positive whole numbers. Cynthia has to guess how
many odd numbers could there possibly be among them if:
a) their sum is odd,
b) their product is even,
c) when you add any two of them, there are more odd sums than even sums.
A.286. Two workers, an old and a young
man, live in the same building, and work in the same factory. It takes the
young man 20 minutes, and it takes the old man 30 minutes to get to work.
One morning the old man left 5 minutes earlier than the young man. How long
does it take the young man to catch up with the old one?
A.287. How many 3-digit divisors does 2001
have?
A.288. In the following number-pyramid
every brick (from the second row up) contains the sum of the two numbers
underneath it. Fill in the blanks.
Please, send your solutions to: