Make the Number 100 Puzzle

Using the numerals 1,7,7,7 and 7 (a "1" and four "7"s) create the number 100.

As well as the five numerals you can use the usual mathematical operations +, −, ×, ÷ and brackets ().

For example: (7+1) × (7+7) = 112 would be a good attempt, but not right, because it is not 100.