Mental Math
What is 23 × 4 + 19?
111
What’s the term for the distance around a circle?
Circumference
What is the sum of the digits in any 2-digit multiple of 9?
9
What two whole numbers multiply to 36 and add up to 13?
9 and 4
What is the smallest positive integer that is divisible by 3, 4, 5, and 6?
A number is increased by 15%, and the result is 253. What was it?
What do we call a number that can be expressed as a fraction of integers?
Rational number
What number has the same number of letters as its value?
Four
I am a 2-digit number. Reversed and added to myself, I equal 121.
77
Solve for x: 2(x + 3) = 4x - 6.
6
What is 375 ÷ 25 × 1.6?
24
What’s the term for the smallest positive number divisible by given numbers?
Least Common Multiple (LCM)
What number do you always get from the 1089 number trick?
I am less than 20 and a multiple of both 2 and 3. What number am I?
6,12,18
111,111,111 x 111,111,111 =
12,345,678,987,654,321
Subtract 387 from 1000, then multiply the result by 0.25.
153.25
What is a rational function?
A ratio of two polynomials
What is the name of the sequence where each number is the sum of the two before it?
Fibonacci sequence
I have two U.S. coins that add up to 30 cents.
One of them is not a nickel.
What are the two coins?
a nickel and a quarter
What temperature is the same in both Celsius and Farenheit?
-40 degrees
What is 51² – 49²?
What does it mean if a set is countably infinite?
Its elements can be listed in a sequence (1-to-1 with natural numbers)
What math object has infinite length but encloses finite area?
Gabriel’s Horn (or Torricelli’s trumpet)
If a student and a half write a paper and a half in a day and a half, how many papers will half a dozen students write in a dozen days?
48
Complete the sequence:
1, 11, 21, 1211, 111221,
312211