Factors and multiples

There are 243 NRICH Mathematical resources connected to Factors and multiples
Zios and Zepts
problem

Zios and Zepts

Age
7 to 11
Challenge level
filled star empty star empty star
On the planet Vuv there are two sorts of creatures. The Zios have 3 legs and the Zepts have 7 legs. The great planetary explorer Nico counted 52 legs. How many Zios and how many Zepts were there?
Mathematical Swimmer
problem

Mathematical Swimmer

Age
11 to 14
Challenge level
filled star filled star filled star
Can you work out how many lengths I swim each day?
What is Ziffle?
problem

What is Ziffle?

Age
7 to 11
Challenge level
filled star empty star empty star
Can you work out what a ziffle is on the planet Zargon?
What Two ...?
problem

What Two ...?

Age
7 to 11
Challenge level
filled star filled star empty star
56 406 is the product of two consecutive numbers. What are these two numbers?
Heads and Feet
problem

Heads and Feet

Age
5 to 7
Challenge level
filled star filled star empty star
On a farm there were some hens and sheep. Altogether there were 8 heads and 22 feet. How many hens were there?
Remainder
problem

Remainder

Age
11 to 14
Challenge level
filled star filled star empty star
What is the remainder when 2^2002 is divided by 7? What happens with different powers of 2?
Number rules - OK
problem

Number rules - OK

Age
14 to 16
Challenge level
filled star filled star empty star
Can you produce convincing arguments that a selection of statements about numbers are true?
X marks the spot
problem

X marks the spot

Age
11 to 14
Challenge level
filled star filled star filled star
When the number x 1 x x x is multiplied by 417 this gives the answer 9 x x x 0 5 7. Find the missing digits, each of which is represented by an "x" .
Really Mr. Bond
problem

Really Mr. Bond

Age
14 to 16
Challenge level
filled star filled star filled star
115^2 = (110 x 120) + 25, that is 13225 895^2 = (890 x 900) + 25, that is 801025 Can you explain what is happening and generalise?
Divisively so
problem

Divisively so

Age
11 to 14
Challenge level
filled star filled star empty star
How many numbers less than 1000 are NOT divisible by either: a) 2 or 5; or b) 2, 5 or 7?