The closest results differ from 677 by 0. They are:

677 = (((100 - 7) - 7) x 7) + 75
677 = ((100 - (7 + 7)) x 7) + 75
677 = ((100 x 7) - 9) - (7 + 7)
677 = ((100 x 7) - 7) - (9 + 7)
677 = (100 x 7) - ((9 + 7) + 7)
677 = (100 x 7) - ((7 + 7) + 9)
677 = ((100 x 7) - (9 + 7)) - 7
677 = (((100 x 7) - 9) - 7) - 7
677 = (((100 x 7) - 7) - 9) - 7
677 = ((100 x 7) - (7 + 7)) - 9
677 = (((100 x 7) - 7) - 7) - 9
677 = (75 x 9) + ((7 + 7) / 7)
677 = ((75 + (7 / 7)) x 9) - 7
677 = ((75 x 9) + 100) - ((7 + 7) x 7)
677 = (75 x 9) + (100 - ((7 + 7) x 7))
677 = ((100 x ((75 - 7) - 7)) - 7) / 9
677 = ((100 x (75 - (7 + 7))) - 7) / 9
677 = ((100 - (7 x (9 - 7))) x 7) + 75
677 = ((75 x 9) - ((7 + 7) x 7)) + 100