mscroggs.co.uk
mscroggs.co.uk
Click here to win prizes by solving the mscroggs.co.uk puzzle Advent calendar.
Click here to win prizes by solving the mscroggs.co.uk puzzle Advent calendar.

subscribe

Puzzles

11 December

Today's number is the number \(n\) such that $$\frac{216!\times215!\times214!\times...\times1!}{n!}$$ is a square number.

Show answer

4 December

Today's number is the number of 0s that 611! (611×610×...×2×1) ends in.

Show answer

10 December

How many zeros does 1000! (ie 1000 × 999 × 998 × ... × 1) end with?

Show answer

Factorial pattern

$$1\times1!=2!-1$$ $$1\times1!+2\times2!=3!-1$$ $$1\times1!+2\times2!+3\times3!=4!-1$$
Does this pattern continue?

Show answer

Square factorials

Source: Woody at Maths Jam
Multiply together the first 100 factorials:
$$1!\times2!\times3!\times...\times100!$$
Find a number, \(n\), such that dividing this product by \(n!\) produces a square number.

Show answer & extension

17 December

In March, I posted the puzzle One Hundred Factorial, which asked how many zeros 100! ends with.
What is the smallest number, n, such that n! ends with 50 zeros?

One hundred factorial

How many zeros does \(100!\) end with?

Show answer & extension

Archive

Show me a random puzzle
 Most recent collections 

Sunday Afternoon Maths LXVII

Coloured weights
Not Roman numerals

Advent calendar 2018

Sunday Afternoon Maths LXVI

Cryptic crossnumber #2

Sunday Afternoon Maths LXV

Cryptic crossnumber #1
Breaking Chocolate
Square and cube endings

List of all puzzles

Tags

functions quadratics christmas scales partitions squares probability wordplay coordinates remainders regular shapes routes speed chalkdust crossnumber arrows floors cryptic clues rectangles logic square roots shape factorials spheres triangles bases division complex numbers sequences volume crosswords addition dice money numbers dates prime numbers folding tube maps hexagons algebra palindromes averages geometry circles sport integration means trigonometry star numbers number integers dodecagons multiples books pascal's triangle factors fractions digits unit fractions sum to infinity lines probabilty taxicab geometry ellipses parabolas proportion perimeter surds shapes people maths odd numbers indices symmetry 2d shapes area irreducible numbers time chocolate cube numbers perfect numbers rugby chess clocks balancing multiplication colouring coins polygons games square numbers triangle numbers crossnumbers calculus planes ave mean menace graphs percentages cryptic crossnumbers grids differentiation doubling angles 3d shapes cards sums advent

Archive

Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2012–2019