The invention discloses a demonstrator comprising a left page and a right page which are movably connected. A model computing region is disposed in the left page and comprises an upper cross bar and a lower cross bar. Abacus rods are arranged between the upper cross bar and the lower cross bar and are provided with multiple beads. Digits with magnets are disposed in the right page and are attracted by a
magnet in the right page. Keyboards are disposed at the bottom of the left page and the bottom of the right page and represent different tones. The model computing region comprises the upper cross bar and the lower cross bar. The abacus rods are arranged between the upper cross bar and the lower cross bar and are provided with the multiple beads. It trains a manipulative capability and a thinking capability to compute by using the abacus. The digits with the magnets are attracted by the
magnet in the right page, are easy to move, and may form new numbers for learning.