How many words can a pen with half refill write?

Can you decipher the below rebus?

PBLUESAISNUERSES

Find the next number in the sequence

1, 2, 6, 21, 88, __?

What type of tree can I carry in my hand?

A man is sitting in a bar when a rich man sits next to him. He turns to the rich man and says, “Did you know I know almost every song that has ever existed?”

The rich man laughs. The man then says, “I bet you all the money you have in your wallet that I can sing a genuine song with a lady’s name of your choice in it. The rich man laughs again and says, “OK, how about my daughter’s name, Jamie Armstrong-Miller?” Minutes later, the man collects his cash and the rich man goes home cashless. What song did the man sing?

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

What do you get if you add 2 to 100 four times?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?