You may also like

problem icon

Consecutive Numbers

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

problem icon

Calendar Capers

Choose any three by three square of dates on a calendar page...

problem icon

Days and Dates

Investigate how you can work out what day of the week your birthday will be on next year, and the year after...

Seven Dwarfs

Stage: 3 Short Challenge Level: Challenge Level:1
Suppose the youngest dwarf is $x$ years old. The sum of the ages of the youngest three is $x+(x+1)+(x+2)=3x+3$, and the sum of the ages of the oldest three is $(x+4)+(x+5)+(x+6)=3x+15$.

We know that $3x+3=42$, so $3x+15=42+12=54$.

This problem is taken from the UKMT Mathematical Challenges.