Algebra
Geometry
Brain Teasers
Pit of Doom
100

An integer is decreased by 2 and then multiplied by 5. If the final result is 85, the original number is...

19

100

The circumference of a circle with diameter 3cm is...

9.42 cm

100

The amount of prime numbers less than 100 are...

25

100

Dylan writes down a list of four integers. He calculates the average of each group of three of the four integers. These averages are 32, 39, 40, 44. What is the largest of the four integers?

59

200

If 2x + 6 = 16, the value of x + 3 is...

8

200

A rectangle has dimensions 13 x 11. Both sides are increased by 2 units. The change in the area of the rectangle is...

52

200

Two years ago, I was three times as old as my brother was. In three years, I will be twice as old as my brother. How old are each of us right now?

17 & 7

200

Jimmy takes 12 hours to finish painting a room. John takes 6 hours to finish painting the same room. The amount of time it will take for them to paint the room working together is...

4 hours

300

In a triangle, the measure of the middle angle is 3 times the smallest angle. The largest angle is 55° larger than the smallest angle. The measure of the angles from smallest to largest is...

25°, 75°, 80°

300

Rectangle A has a length of 6cm and area 36cm2.

Rectangle B has a length of 12cm and area 36cm2.

Rectangle C has a length of 9cm and area 36cm2.

The width of the rectangle with the smallest width is...

3cm (Rectangle B)

300

Using only the addition sign and eight digit 8s, add up to the number 1000.

888 + 88 + 8 + 8 + 8 = 1000

300

What is the integer formed by the rightmost two digits of the integer equal to 4127 + 5129 + 7131?

52

400

161 guests attended a banquet. Three servers provided their beverages. The first server helped 2 times as many as the second and the third helped 2 times as many as the first. The number of guests the third server helped is...

92

400

Angles A and B are complementary and the measure of angle A is twice the measure of angle B. The measures of angles A and B are...

60°, 30°

400

You are in a cookie factory and need to make a huge batch of chocolate chip cookies. The recipe calls for exactly 4 cups of sugar. The problem is that you only have two buckets. One that holds 5 cups and the other that holds 3. With these buckets, how can you measure out the 4 cups needed.

3 into 5, 3 into 5, only 1 cup left in 3, dump out 5, transfer 1 from 3 to 5, fill up 3, add 3+1 in the 5 container to get 4 cups
400

At a meeting of 9 people, each participant said that they shook hands with exactly 3 people. Explain why this is not possible.

The total amount of handshakes has to be even as there are always 2 people involved in a handshake.

500

Three taxi drivers are working at an airport. The first transported 17 passengers in a day. The second drove 6 more than the first one and the third drove 2 less than the second one. The number of passengers they transported altogether in the day is...

61

500

A man takes a piece of cake with an angle of 60° from a birthday cake with radius 10cm and height 6cm. The volume of his slice of cake is...

314cm3

500

Old Granny Adams left half her money to her granddaughter and half that amount to her grandson. She left a sixth to her brother and donated the remaining $1000 to charity. The amount she left altogether is...

$12,000
500

Alice knows that 3 red cards and 3 black cards will be revealed to her one at a time in random order. Before each card is revealed, Alice must guess its color. If Alice plays optimally, the expected number of cards she will guess correctly is m/n where m and n are relatively prime positive integers. The value of m + n is...

41 + 10 = 51

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