Rational methods of oral calculations (4-11 cl.)

Direction:mathematical
Form of work:troublesomely

Purpose:
To study rational methods of computation, for the production of which it is enough oral counting or the use of pencil and paper, to help yourself and your comrades master computational skills perfectly, developing memory and attention.Tasks:

1. Get acquainted with the method of speed calculation by Jacob Trachtenberg;
2. To study the reception of cross multiplication when acting with two-digit numbers;
3. Get acquainted with other interesting techniques of oral calculations.

The presentation contains 11 slides (188 KB)