Not Roman numerals

The letters \(I\), \(V\) and \(X\) each represent a different digit from 1 to 9. If
$$VI\times X=VVV,$$
what are \(I\), \(V\) and \(X\)?

Show answer

Backwards fours

If A, B, C, D and E are all unique digits, what values would work with the following equation?
$$ABCCDE\times 4 = EDCCBA$$

Show answer

10 December

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

Show answer

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


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


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


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