13

On the back of a dollar bill, there are 13 steps on the pyramid. The motto above the pyramid has 13 letters (annuit coeptis). E pluribus unum, written on the ribbon in the eagle's beak, has 13 letters. 13 stars appear over the eagle's head. 13 stripes are on the shield. 13 war arrows are in the eagle's left talon. The olive branch in the eagle's right talon has 13 leaves.