Use BC, AD, a.m., p.m., No. and $ Only With Specific Dates, Times, Numbers, and Amounts

B.C., A.D., a.m., p.m., No. and $ are abbreviations which are used only in specific cases; they’ll need a direct modifier immediately before or after them. Used this way, these particular abbreviations are acceptable for use in formal writing. If the case is general, though – that is, there’s no direct modifier – be sure to write out the word in full.

Alexander the Great lived B.C.

Alexander the Great lived before Christ.

Alexander the Great lived around 300 B.C.

The Battle of Hastings happened A.D.

The Battle of Hastings was in 1066 A.D.

The Battle of Hastings was more than a thousand years Anno Domini (the Year of the Lord).

I shall see you in the a.m.

I shall see you in the morning.

I shall see you at 10 a.m.

We’ll have the staff meeting this p.m.

We’ll have the staff meeting this afternoon.

We’ll have the staff meeting at 3 p.m.

I know you live on Main Street, but I don’t know the house No.

I know you live on Main Street, but I don’t know the house number.

My house is No. 385 Main Street.

The charity required a lot of $.

The charity required a lot of money.

The charity required $5000.