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

Sunday Afternoon Maths XIX

 Posted on 2014-06-29 

Multiples of three

If the digits of a number add up to a multiple of three, then the number is a multiple of three. Therefore if a two digit number, \(AB\) (first digit \(A\), second digit \(B\); not \(A\times B\)), is a multiple of three, then \(A0B\) is also a multiple of three.
If \(AB\div 3=n\), then what is \(A0B\div 3\)?

Show answer & extension

Tags: numbers

Dartboard

Concentric circles with radii 1, \(\frac{1}{2}\), \(\frac{1}{3}\), \(\frac{1}{4}\), ... are drawn. Alternate donut-shaped regions are shaded.
What is the total shaded area?

Show answer & extension

If you enjoyed these puzzles, check out Advent calendar 2023,
puzzles about indices, or a random puzzle.

Archive

Show me a random puzzle
 Most recent collections 

Advent calendar 2023

Advent calendar 2022

Advent calendar 2021

Advent calendar 2020


List of all puzzles

Tags

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

Archive

Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2012–2024