The combination for opening a safe is a three – digit number made up of different digits. How many different combinations can you make using only digits 1, 3, and 5?
A) 2 B) 3 C) 4 D) 5 E) 6
A workshop in Florida for 2009 Math Kangaroo Competition. Visit Math Kangaroo webpage for registration and information about the competition: www.mathkangaroo.org
The combination for opening a safe is a three – digit number made up of different digits. How many different combinations can you make using only digits 1, 3, and 5?
A) 2 B) 3 C) 4 D) 5 E) 6
The numbers 34 and 142 have the same sum of their digits (3+4=7 and 1+4+2=7). What is the first number greater than 2007 such that the sum of its digits is the same as the sum of the digits of 2007?
A) 2016 B) 2115 C) 2008 D) 7002 E) 2070
Betty likes calculating the sum of the digits that she sees on her digital clock (for instance, if the clock shows 21:17, then Betty gets 11). What is the biggest sum she can get if the clock is a 24-hour clock?
A) 24 B) 36 C) 19 D) 25 E) another answer
Sophie draws kangaroos: a blue one, then a green, then a red, then a black, a blue, a green, a red, a black, and so on…What color is the 29th kangaroo?
A) blue B) green C) red D) black E) it’s impossible to know
The sum of the numbers in each ring below should be 55. What is the value of A?
A) 9 B) 10 C) 13 D) 16 E) 17
Anna wrote a 2-digit number. Ben created a 4-digit number by copying Anna's number twice. Then Anna divided Ben's number by her number. What was the result she got?
A) 100 B) 101 C) 1000 D) 1001 E) 10
Bill thought of an integer number. Nick multiplied this number either by 5 or by 6. John added either 5 or 6 to Nick’s result. Last, Andrew subtracted either 5 or 6 from John’s result. The final result obtained was 73. What was Bill’s number?
A) 10 B) 11 C) 12 D) 14 E) 15
Harry Potter let an owl out at 7:30 a.m. to deliver an important message to his friend Ron. The owl delivered the envelope at 9:10 a.m. An owl flies 4 km in 10 minutes. What was the distance between Harry and Ron?
A) 14 km B) 20 km C) 40 km D) 56 km E) 64 km
What is the 2007th letter in the sequence KANGAROOKANGAROOKANG… ?
A) K
B) A
C) N
D) R
E) O
There were 60 birds on three trees. At some moment 6 birds flew away from the first tree, 8 birds flew away from the second tree, and 4 birds flew away from the third tree. After that, it turned out that the number of birds on each tree was the same. How many birds were there on the second tree in the beginning?
A) 26 B) 24 C) 22 D) 21 E) 20
The square in the figure is a mini-sudoku: the numbers 1, 2, and 3 must be written in the cells so that each of them appears in each row and in each column. Harry started to fill in the square. In how many ways can he complete the task?
A) 1 B) 2 C) 3 D) 4 E) 5
The odometer of my car indicates 187569. All the digits of this number are different. After how many more kilometres will this happen again?
A. 1 B. 21 C. 431 D. 12431 E. 13776
Robert made a tunnel using some identical cubes (fig.1). When he got bored, he rearranged the tunnel into a complete pyramid (fig.2). How many cubes from the original tunnel did he not use for the pyramid?
A. 34 B. 29 C. 22 D. 18 E. 15
From her window Karla looks at the wall of a house. There she can see the silhouette of a rectangular flag flying in the wind. At five different moments she draws the silhouette. Which of the 5 pictures cannot be right unless the flag is torn?
The face of a clock is cracked into 4 pieces. The sums within the parts are consecutive numbers. Provided there is only one possible way to crack it, the face would look like:
A.14 cm. B. 10 cm. C. 7 cm. D. 6 cm. E. 4 cm