ID 685

  K9Which gives the largest answer?

ID 688

  K9Which gives the largest answer?

ID 756

  K9Which gives the smallest answer?

ID 766

  K9What is 111% of a number, if 132 is 11% of that number?

ID 1020

  K9How many 2-digit integers are there in which the sum of the digits is equal to 6?

ID 1070

  K9If 120 is divided into three parts proportional to 7, 8 and 9, then the largest number is

ID 1207


1000000012 – 999999992

ID 1212

  K9How many digits are in the product of

2101 and 599?

ID 1554

  K9If you write all of the whole numbers from 1 through 1000, how many numbers have the digit 4?

ID 1839

  K9How much is

0 - 1 + 10 - 100 + 1000 - . . . -1010+1011

ID 1881

  K9What is the difference between the sum of the first 2012 even positive numbers and the sum of the first 2012 odd positive numbers?

ID 1980

  K9A man is eating a pizza.
During the first day he eats a half of the pizza.
On the second day he eats 1/3 of the remaining part of the pizza.
The third day he eats 1/4 of what is left, and the fourth day he eats 1/5 of what still remains.

He then stops because the last piece was not fresh.

What fraction of the original pizza is still available?

ID 2028

  K9An abundant number is a positive integer whose factors (other than the number itself) have a sum greater than the number.

Which number is not abundant?

ID 2229

  K9When freezing, milk increases its volume by 1/15.

How will the frozen milk volume decrease when it melts?

ID 2268

  K9Work out the sum of all the integers below 100.

ID 2276

  K9A number is said to be perfect if it is equal to the sum of its proper divisors, that is all divisors excepting the number itself.

For example, 6 is a perfect number because 1 + 2 + 3 = 6 .

What is the largest 3-digit perfect number?

ID 2283

  K9A prime number is an integer number that has no positive divisors other than 1 and itself.

Which is not a prime number?

ID 3221

  K9If 168 is divided into three parts proportional to 7, 8 and 9, then the smallest number is

ID 3318

  K9The North American emergency telephone number is 911.
It is a prime number.

A prime number is an integer that has no positive divisors other than 1 and itself.

What is the next prime number?

ID 3356

  K9Sebastian achieved these scores in his exams.

Which was his worst result?

ID 3392

  K9Multiply all the digits of each license plate without using a calculator.

Find the plate with the smallest total.

ID 3412

  K9On this target, I scored exactly 90.

How many shots did I fire?

ID 3432

  K9How many 2-digit integers are there in which the sum of the digits is equal to 6?

ID 3537

  K9How many positive integer numbers are twice the sum of their digits?

ID 3649

  K9What is the smallest possible difference between two integer numbers that, when multiplied together, produce12345?

ID 3774

  K9How many of the three-digit integers are multiples of the first five positive integers?

ID 3779

  K9Fill in each empty place between the numbers with one of the symbols +, -, x or /, with each symbol used exactly once.
No parentheses are allowed.

What is the least possible absolute value of the result?

ID 3784

  K9Find the sum of the first 100 odd positive numbers:

1 + 3 + . . .

ID 3918

  K9Find the average of all positive integers divisible by 3 and smaller than 1000.

ID 3964

  K9Write natural numbers 1, 2, . . .100 in a row so that the difference between any two adjacent numbers is smaller than N.

Find the maximum possible N.

ID 4039

  K9In a class, 7 students walk to school, two fifths ride the bus, and 32% are dropped off by their parents.

What number is the largest?

ID 4040

  K9In a class, 7 students walk to school, two fifths ride the bus, and 32% are dropped off by their parents.

How many students ride the bus?

ID 4051

  K9How many digits are there in the largest positive integer, in which each digit is at least the sum of all the digits to its left?

ID 4182

  K9What is the smallest result that can be achieved?

AB6 + BC7

Different letters in the expression are replaced with different numbers from 0 to 9 and there are no leading zeros.

The question is typical for PISA Test.

PISA stands for Programme for International Student Assessment.

ID 4235

  K9If the sum of 999 positive integers is equal to 1000 what is their product?

ID 4297

  K9What gives the largest result?

ID 4376

  K9Which number could not be written as a sum of 3 consecutive numbers?

ID 4501

  K9Find the first of the four consecutive integer numbers if their sum is -66.

ID 4537

  K9January 1st, 2014 was a Wednesday.

How many Wednesdays occurred in 2014?

2014 was not a leap year.

ID 4648

  K9Divide 55 into two parts so that one will be 150 percent of the other.

What is the smallest number?

ID 4830

  K9The product of 33 positive integers is 33.

What is the sum of the numbers?

ID 4906

  K9Estimate the product of the digits of the number 7777777.

ID 4921

  K9Find the midpoint between the points one fifth and fifteen.

ID 4959

  K9100 is to 121 as 10 to . . .

ID 5006

  K9Use four 9's and any math signs to make 100.

How many sign '+' did you use?

ID 5378

  K9The maximum capacity of the Wembley Stadium, London, England, is 90,000.
The stadium contains 2,618 toilets, more than any other venue in the world.
There are 78,540 people in the stadium now.

If they all go to the toilets and they are evenly distributed, how long will be the queue?

We suppose that there is 1 seat per toilet.

ID 5422

  K9The ratio of two numbers is 3 : 5.
The difference between the numbers is 8.
What is the sum of the two numbers?

ID 5436

  K9Gerry writes the first 5 integers.
He puts either sign "+" or "x" between the numbers.

What is the largest result he can get?

He does not use parentheses (brackets).

ID 5439

  K9When N copies of the integer N are multiplied together, the product is 256.

What is N?

ID 5644

  K9How many positive integers that are strictly less than one hundred are evenly divisible by both 2 and 3?

ID 5758

  K9 39 x 93 =

ID 6034


22 + 20 + 21 + 27

ID 6248

  K922017 - 22016 = ?

ID 6533

  K9Put four operations signs between the numbers 5, 4, 3, 2, and 1 to make the lowest possible result.

What will it be?

Don't change the order of the numbers, use all four signs, and don't use brackets.

ID 6598

  K9If A, B, and C are different digits, how many different solutions does the number puzzle have?

ID 6725

  K9Spotting patterns is very important.

Can you spot which number doesn't fit the pattern?

1,   2,   5,   14,   42,   122,   . . .

Author: Leslie Green

ID 6976

  K9Cross out 5 digits from the number


so that the remaining number is as small as possible.

What are the first five digits of the result?

ID 7028

  K9Which number represents the smallest amount?

ID 7192

  K9Do this in your head. No pen, paper, or calculator.

Start with 3
multiply the result by 3
add one
multiply the result by 3
add one

Which is the correct answer?

ID 7325

  K9What is meant by the square root of a number?