The letter D
The Letter "D"
The letter DDAYDECADECENTURY
The answer to the riddle is the letter "e." It appears once in the word "year" and twice in the word "decade."
e
The letter "m" :DOnce in a minute, twice in a moment, and never in a second.
The Letter "D"
Letter e
The letter DDAYDECADECENTURY
"twice per decade" = 2 / 10 years = 1nce per five years
Letter "m"
the letter n ;)
The letter "e."
It depends on the decade. Sometimes once, sometimes twice.
The Mongols in 1223 and in 1237. Under King Charles XII Sweden invaded Russia at least twice during the first decade of the 18th Century
The letter DDAYDECADECENTURY
The letter E
The Letter "e"