ABACUS International Math Challenge
for
3rd and 4th graders
October, 1999
A.137. a) Find the greatest 4-digit number
with all different digits where the product of the digits is 216.
b) Find the smallest positive whole number in which the product of the
digits is 200.
A.138. Write the numbers 1, 2, 3, 4, 5,
and 6 in the circles so that the sums of the numbers on each of the three
sides are the same.
O
OO
OOO
A.139. Fill in the blanks using all of
the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 so that the sums of
the numbers in each row and column is the same as the number written at
the right end of that row or bottom of that column.
| X |
|
|
|
19 |
| |
X |
|
|
22 |
| |
|
X |
|
20 |
| |
|
|
X |
17 |
| 20 |
19 |
17 |
22 |
X |
A.140. There are history, math and physics
books in a library. The covers of the books are red, green, or blue. We
know that the covers of the history books are not blue, the covers of the
math books are either green or blue, and that the covers of the physics
books are neither red nor green. What is the color of the covers of the
history books?
A.141. Four humble guys, Hubert, Hubby,
Harold and Harry, made the following four humble statements:
Hubert: "Hubby is the most humble."
Hubby: "Harold is the most humble."
Harold: "I am not the most humble."
Harry: "I am not the most humble."
As it turned out, only one of these four humble statements is true.
Who is the most humble guy?
A.142. Place 10 points on 5 straight lines
so that every line contains 4 of the points.
A.143. Place parentheses in the following
expression so that its value is:
a) 50
b) the greatest possible;
c) the lowest possible.
A.144. Put the numbers 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, and 13 into three groups so that none of the groups
contains two such numbers that their difference is in that group, too. (For
example: 8, 5 and 3 cannot be in the same group because 8-5=3.)
Please, send your solutions to: