Tag: numbers

Interview Questions

• Writing 100 as a sum of consecutive numbers
• The person whose age is the square root of the year
• The number equal to the sum of the cubes of its digits
• The cannonballs that make a square and a pyramid
• The number that rotates when multiplied
• A quick test for divisibility by 7
• Which is bigger, e to the pi or pi to the e?
• The number that equals the sum of the factorials of its digits
• How many digits does 2 to the 1000 have?
• A hundred animals for a hundred pounds
• Kaprekar's constant, 6174
• The last digit of seven to the seven to the seven
• The last two digits of seven to the power 2024
• Can the average of two consecutive primes be prime?
• The missing digit of two to the twenty-ninth
• The four-digit number that reverses when multiplied by four
• Which numbers cannot be a sum of consecutive numbers?
• Two numbers whose sum equals their product
• Why one less than a prime's square is always a multiple of 24
• The number that is one short of every multiple
• The number that describes its own digits
• The smallest number divisible by everything up to 20
• The smallest number with exactly twelve divisors
• A number that is both a square and a cube
• The square root of 12345678987654321
• Postage from 5 and 7 cent stamps
• Why the sum of the first n cubes is always a perfect square
• The taxicab number
• The 1089 trick
• The nine-digit number whose every prefix divides
• Three ages that add to 20 and multiply to 240
• How many zeros end 25 factorial in base twelve?
• 12345679 times 9, and its friends
• Make 24 from 8, 8, 3 and 3
• Two-digit numbers that are seven times their digit sum
• The two-digit number that is the square of its digit sum
• Two primes that add up to 101
• Two to the hundred against ten to the thirty
• When is 2 to the n plus 1 divisible by 3?