ABACUS International Math Challenge
for
3rd and 4th graders
February, 2002
A.297. On his magic carpet, Aladdin arrived
to a city where people do not know the digit 3. They count like this: 1,
2, 4, 5, ..., 11, 12, 14, 15, ... What number do they use for our 100?
A.298. In a nearby desert live the sand-eater
beasts. 2 beasts can eat 2 tons of sand in 2 hours. How much sand can 6
beasts eat in 6 hours with the same appetite?
A.299. In the Cave of Wonders Aladdin found
25 necklaces in one of the boxes. Every necklace had either a diamond or
a ruby or both stones in it. 10 of them had diamond and 6 of them had both
stones in them. How many necklaces had ruby in them?
A.300. Princess Jasmine is trying to divide
the following table cloth along the seams into two identical (same size
and same shape) sections. She wants to paint one section blue, and the other
section yellow. Help Jasmine to make as many different table cloths as possible.
A.301. Iago, the parrot, was getting dizzy
trying to count how many squares and how many triangles there are on the
following carpet design. How many of each do you see?
A.302. In two boxes there are a total of
126 emerald stones. If we put in one box as many as one third of the stones
already in it, and we took one third of the stones out of the other box,
then both boxes would have the same number of stones in them. How many stones
were there in the boxes originally?
A.303. To hem around a rectangular-shaped
magic carpet, you need 5520 mm of ribbon. The length of the carpet is 15
cm longer than twice the width of the carpet. They sewed fringes 3 cm apart
on the shorter sides of the carpet. How many fringes are there on the carpet?
A.304. Aladdin and the Genie are playing
a game. Aladdin says to the Genie: "Put two golden coins in one of
your hands, and put five golden coins into your other hand. Whatever you
have in your left hand, multiply its value by an even number. Whatever you
have in your right hand, multiply its value by an odd number. Tell me the
sum of these two products, and then I will tell you how many coins you have
in your left hand and in your right hand." The Genie said: 30. How
many coins are there in the Genie's left hand?
Please, send your solutions to: