### There are 7 results

Broad Topics >

Numbers and the Number System > Factorials

##### Age 14 to 16 Challenge Level:

Consider numbers of the form un = 1! + 2! + 3! +...+n!. How many such numbers are perfect squares?

##### Age 14 to 16 Challenge Level:

Lyndon chose this as one of his favourite problems. It is
accessible but needs some careful analysis of what is included and
what is not. A systematic approach is really helpful.

##### Age 14 to 16 Challenge Level:

How many zeros are there at the end of the number which is the
product of first hundred positive integers?

##### Age 11 to 14 Challenge Level:

6! = 6 x 5 x 4 x 3 x 2 x 1. The highest power of 2 that divides
exactly into 6! is 4 since (6!) / (2^4 ) = 45. What is the highest
power of two that divides exactly into 100!?

##### Age 14 to 16 Challenge Level:

How many noughts are at the end of these giant numbers?

##### Age 11 to 14 Challenge Level:

Find the highest power of 11 that will divide into 1000! exactly.

##### Age 11 to 14 Challenge Level:

I have forgotten the number of the combination of the lock on my
briefcase. I did have a method for remembering it...