Can anyone tell me a word in the English dictionary which has a silent 'z'?

Can you solve this tricky maths equation problem by replacing it? mark with the correct symbol?

19834 -----: 187
15921 -----: 153
17561 -----: 139
13734 -----: ???

Eight Chelsea player makes the following statements :

1. Seven of us are lying here.
2. Six of us are lying here.
3. Five of us are lying here.
4. Five of us are lying here.
5. Four of us are lying here.
6. Three of us are lying here.
7. My name is Torres.
8. My name is Lampard.

The last two are Lampard and Torres or maybe Torres and Lampard.
So can you deduce which of the last two is Lampard or Torres?

Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How?

What four weights can be used to balance from 1 to 30 pounds?

There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

Can you write down eight eights so that they add up to one thousand?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?