mscroggs.co.uk
mscroggs.co.uk

subscribe

Puzzles

Subsum

1) In a set of three integers, will there always be two integers whose sum is even?
2) How many integers must there be in a set so that there will always be three integers in the set whose sum is a multiple of 3?
3) How many integers must there be in a set so that there will always be four integers in the set whose sum is even?
4) How many integers must there be in a set so that there will always be three integers in the set whose sum is even?

Show answer & extension

If you enjoyed this puzzle, check out Sunday Afternoon Maths LII,
puzzles about factors, or a random puzzle.

Archive

Show me a random puzzle
 Most recent collections 

Advent calendar 2025

Advent calendar 2024

Advent calendar 2023

Advent calendar 2022


List of all puzzles

Tags

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

Archive

Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2012–2026