Today’s puzzle appeared on the TV show Only Connect. Can you work out what comes fourth in the sequence?
Scroll down for a clue and further down for the answer.
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Clue: This puzzle relates to the planets in our Solar System.
Scroll down for the answer.
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Answer:
Each rectangle represents the number of known planets in our Solar System by century.
The first rectangle, ’18th 6 + U = 7′ represents: 18th century, 6 planets plus Uranus equals 7 planets’. In other words, Uranus was discovered in the 18th century, which gave our model of the Solar system 7 planets.
The last rectangle needs to contain ’21st 9 – P = 8′. This represents: 21st century, 9 planets minus Pluto equals 8 planets. In other words, during the 21st century, Pluto was demoted to a dwarf planet, leaving 8 planets in our Solar System.
Puzzle a Day 