Place value

problem

Oddly

Age

7 to 11

Challenge level

Find the sum of all three-digit numbers each of whose digits is odd.
problem

One Million to Seven

Age

7 to 11

Challenge level

Start by putting one million (1 000 000) into the display of your calculator. Can you reduce this to 7 using just the 7 key and add, subtract, multiply, divide and equals as many times as you like?
problem

Song Book

Age

7 to 11

Challenge level

A school song book contains 700 songs. The numbers of the songs are displayed by combining special small single-digit cards. What is the minimum number of small cards that is needed?
game

Nice or Nasty for Two

Age

7 to 14

Challenge level

Some Games That May Be Nice or Nasty for an adult and child. Use your knowledge of place value to beat your opponent.
problem

Cayley

Age

11 to 14

Challenge level

The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?
problem

Not a Polite Question

Age

11 to 14

Challenge level

When asked how old she was, the teacher replied: My age in years is not prime but odd and when reversed and added to my age you have a perfect square...
problem

Writ Large

Age

11 to 14

Challenge level

Suppose you had to begin the never ending task of writing out the natural numbers: 1, 2, 3, 4, 5.... and so on. What would be the 1000th digit you would write down.
problem

Back of the Queue

Age

11 to 14

Challenge level

Weekly Problem 48 - 2013
What is the remainder when the number 743589 × 301647 is divided by 5?
problem

Football Sum

Age

11 to 14

Challenge level

Find the values of the nine letters in the sum: FOOT + BALL = GAME
problem

Seven Up

Age

11 to 14

Challenge level

The number 27 is special because it is three times the sum of its digits 27 = 3 (2 + 7). Find some two digit numbers that are SEVEN times the sum of their digits (seven-up numbers)?