Multiple choice general knowledge math & puzzles 1, 4, 9, 25, 49, ---- 100 121 81 144 Reveal answer Fill a bubble to check yourself B Correct answer Explanation The series consists of squares of prime numbers: $1^2=1$ (though 1 is not prime, it fits the square sequence), $2^2=4$, $3^2=9$, $5^2=25$, $7^2=49$. The next prime number is 11, and $11^2 = 121$. 81 ($9^2$) is skipped because 9 is composite.