First Appearances of Letters

One thousand is the first number that, when spelled out, contains an a. (One hundred and one if you count the "and.")
One billion is the first number that contains a b.
One octillion is the first number that contains a c.
One hundred is the first number that contains a d.
Zero is the first number that contains an e. Starting from one, it's one.
Four is the first number that contains an f.
Eight is the first number that contains a g.
Three is the first number that contains an h.
Five is the first number that contains an i.
The letters j and k do not appear in the English spelling of any cardinal number.
Eleven is the first number that contains an l.
One million is the first number that contains an m.
One is the first number that contains an n.
Zero is the first number that contains an o. Starting from one, it's one.
One septillion is the first number that contains a p.
One quadrillion is the first number that contains a q.
Zero is the first number that contains an r. Starting from one, it's three.
Six is the first number that contains an s.
Two is the first number that contains a t.
Four is the first number that contains a u.
Five is the first number that contains a v.
Two is the first number that contains a w.
Six is the first number that contains an x.
Twenty is the first number that contains a y.
Zero is the first and only number that contains a z. (One zillion is not a real number.)

Seven is the first number not to contain any letter for the first time.

One octillion, the first number containing a c, is the largest number to contain any letter for the first time.