Which of the following numbers will replace the question mark (?) in the given series? 270, 241, 212, ?, 154, 125

Which letter-cluster will replace the question mark (?) to complete the given series?

BRCQ, EPFO, ?, KLLK, NJOI

Which of the following numbers will replace the question mark (?) in the given series?

$$ 69,65,67,63, ?, 61 $$

Which of the following numbers will replace the question mark (?) in the given series?

$5,20,60,240,720$, ?