SUM of numbers in a sequence

gdougher 

If you're on 365 with access to LAMBDA, there's an elegant solution available.

First, I created dynamic ranges for Service date, hours, and amount.

Created a named item for the Header:

={"Date From", "Date To", "Hours", "Amount"}

Obtained the Week Number:

=MAP(sdate, LAMBDA(e, WEEKNUM(e)))

Summarize LAMBDA:

=LAMBDA(a,v,LET(
    f, FILTER(HSTACK(sdate, hours, amount), WNum = v),
    VSTACK(a, HSTACK(MIN(TAKE(f, , 1)), MAX(f), SUM(TAKE(DROP(f, , 1), , 1)), SUM(TAKE(f, , -1))))
))

Sheet level formula:

=REDUCE(Header,UNIQUE(WNum),Summarize)