Analysis: In this question, 96 is converted into (100-4) by using the law of subtraction and distribution, and then the operation is made simple by using the law of multiplication and association.

0. 125×96

=0. 125×( 100-4)

=0. 125× 100-0. 125×4

= 12.5-0.25

= 12

2、33333x44444+66666x77778

Analysis: 33333x44444 can be converted into 6666× 22222, extracted from the convention 6666, converted into 6666× (2222+77778), and then calculated by the multiplication and distribution law.

33333x44444+66666x77778

=33333×2×22222+66666×77778

=66666×22222+66666×77778

=66666×(22222+77778)

=66666× 100000

=6666600000

3、30-(3.8+0.75)

Analysis: This question mainly uses the law of additive combination distribution. First, it converts 3.8 into (4-0.2) and 0.75 into (1-0.25). Then, it uses additive commutative law to calculate the integer first, and then the decimal. Finally, the brackets are removed by using the law of addition and combination.

30-(3.8+0.75)

=30-[(4-0.2)+( 1-0.25)]

=30-[(4+ 1)-(0.2+0.25)]

=30-(5-0.45)

=30-5+0.45

=25.45

4、3.6×2.5

Analysis: This problem transforms 3.6 into 9×0.4 by multiplication and division, and then makes the operation simple by multiplication and division exchange.

3.6×2.5

=9×0.4×2.5

= 1×9

=9

5、555× 15+ 1 1 1×25

Analysis: This question first converts 555 into 1 1 1×5, and then uses the multiplication and division method to extract the common divisor to calculate.

555× 15+ 1 1 1×25

= 1 1 1×5× 15+ 1 1 1×25

= 1 1 1×(5× 15)+ 1 1 1×25

= 1 1 1×75+ 1 1 1×25

= 1 1 1×(75+25)

= 1 1 1× 100

= 1 1 100

6、98×8/99

Analysis: In this question, 98 is converted into (99- 1) by using the law of subtraction and distribution, and then the operation is simplified by using the law of multiplication and association.

98×8/99

=(99- 1)×8/99

=99×8/99- 1×8/99

=8-8/99

=7 and 9 1/99

7、0.9+9.9+99.9+999.9+9999.9

Analysis: Find the law first, and the difference between five numbers is 0. 1, which can be rounded off. Rounding method is used for conversion first, and then the disjunction is calculated by the law of addition and association (a+b)+c=a+(b+c).

0.9+9.9+99.9+999.9+9999.9

=( 1-0. 1)+( 10-0. 1)+( 100-0. 1)+( 1000-0. 1)+( 10000-0. 1)

= 1+ 10+ 100+ 1000+ 10000-0. 1×5

= 1 1 1 1 1-0.5

= 1 1 1 10.5