Calculation by formula: 5 / 101 × 1 / 2 △ 2 / 5 12 △ 14 / 4 × 7 / 8

Calculation by formula: 5 / 101 × 1 / 2 △ 2 / 5 12 △ 14 / 4 × 7 / 8

5/101×1/2÷2/5
=5/202x5/2
=25/404
12÷14/4×7/8
=24/7x7/8
=3

4.25 △ 2.5 × 101-1.7 simple calculation

A simple algorithm for multiplying 1999 by 0.5%, 1997 by 0.3% and 0.12% of 1999

The title should be wrong, according to your title is difficult to use a simple algorithm, but if changed to the following title can be
A simple algorithm of 1999 times 0.5, 1997 times 0.3 and 1999 1.2
1997×0.3/1999×0.5+1.2/1999
=1997×0.6/1999+2×0.6/1999
=（1997+2）×0.6/1999
=0.6

When learning mathematics in senior one, I always see what the book says to find zero
Which friend told me the zero point partition method

(1) In this paper, we have obtained x = 1, x = 1, x = 1, x = 2 (Ⅰ) when x ＜ - 1, when x 124; - 1, when x | - 1-x | - 1 | - 1 | - 1-x | - 2 | - 1 | - 1-x 124124\124\\124\\124\\\\124\\\\\\\\\\\\\\\\\\\\x-2 | = (?)