1 Lecture on Fast Computing and Clever Computing

1. Simple addition operation

( 1)A+B=B+A

(2)(A+B)+C=A+(B+C)

2. Simple operation of subtraction

( 1)A-B-C=A-(B+C)

(2)A-(B-C)=A-B+C

(3)A-B=A+C-B-C

Addition and subtraction at the same level, MINUS sign outside parentheses,

Add or delete brackets, and the numbers in brackets should be changed.

3. Simple multiplication operation

( 1)A×B=B×A

(2)(A×B)×C=A×(B×C)

(3)(A B)×C=A×C B×C

4. Simple operation of division

( 1)a \b \c = a \(b×C)

(2)a \b×C = a \b \c

(3)A÷B=(A×C)÷(B×C)

Multiplication and division are the same level operations, and semicolons are outside parentheses.

Add or delete brackets, and the numbers in brackets should be changed:

The multiplication symbol should be changed to the division symbol, and the division symbol should be changed to the multiplication symbol.

→ The example is detailed.

Example 125+53+75+78+47

Original formula =(25+75)+(53+47)+78.

= 100+ 100+78

=278

Example 291+90+88+92+93+84+85+95+97

The original formula = (90+1)+90+(90-2)+(90+2)+(90+3)+(90-6)+(90-5)+(90+5)+(90+7)

=90×9+( 1+0-2+2+3-6-5+5+7)

=8 10+5

=8 15

Example 3 1200-856- 144

Original formula = 1200-(856+ 144)

= 1200- 1000

=200

Example 47869-(234+869)

Original formula =7869-234-869

=7869-869-234

=7000-234

=6766

Example 5 1943-( 132-57)

Original formula = 1943- 132+57.

= 1943+57- 132

=2000- 132

= 1868

Example 61-2+3-4+5-6+7-8+9-10+1-12+13-/kloc-0

The original formula =1+(3-2)+(5-4)+(7-6)+(9-8)+(11-kloc-0/0)+(13-)

=8

Example 7950÷25

Original formula =950×4÷25×4

=3800÷ 100

=38

Example 899×22+33×34

Original formula =33×3×22+33×34.

=33×(3×22+34)

=33× 100

=3300

Example 925×32× 125

Original formula =25×4×8× 125.

=(25×4)×(8× 125)

= 100× 1000

= 100000

Example 10325+46- 125+54

Original formula =(325- 125)+(46+54)

=200+ 100

=300