We use this expression to give a total number.
You can use this phrase in ………… language.
Spoken
Written
Informal
Formal
Example 1
A: How many people went on the trip to England?
B: There were about 10 of us altogether. I thought there would be more.
Example 2
A: Was it an expensive trip?
B: I spent about £150 altogether. I thought it would be worse