=7× 1/7-7/ 16× 1/7

= 1- 1/ 16

= 15/ 16

(Note that since the denominator of 1/7 is exactly the same as the numerator of the two numbers in brackets, multiplication and division should be used. )

2、3/7×5/6+4/7×5/6

=(3/7+4/7)×5/6

= 1×5/6

=5/6

(Because the sum of 5/6, 3/7 and 4/7 of the two multiplications is equal to 1, the multiplication distribution law is adopted. )

3、 14/ 15×( 1/2-3/7)

= 14/ 15× 1/2- 14/ 15×3/7

=7/ 15-2/5

= 1/ 15

(14 is a multiple of 7, and it is a multiple of 2, so it is more convenient to subtract points by multiplication and division. )

4、 13/ 16+ 13/ 16× 15+ 15/ 12

= 13/ 16× 1+ 13/ 16× 15+ 15/ 12

= 13/ 16× 16+ 15/ 12

= 13+ 15/ 12

= 14+0/4

(13/ 16 appears twice, and the multiplication distribution law can be used. The single 13/ 16 here can be regarded as 13/ 16× 1).

5、24×( 1/2+2/3+3/4+ 1/6+ 1/8)

=24× 1/2+24×2/3+24×3/4+24× 1/6+24× 1/8)

= 12+ 16+ 18+4+3

=53

(The denominators of the fractions in brackets are all factors of 24, so it is quite convenient to multiply them separately. )

6、25× 1 1/24

=( 1+24)× 1 1/24

= 1× 1 1/24+24× 1 1/24

= 1 1/24+ 1 1

= 1 1 1 1/24

It looks complicated because 25 and 24 are inseparable. But 25 is close to 24, which can be divided into 1+24, which can be calculated by multiplication and division, and then divided by)

As long as the multiplication and division method is used in these six problems, the calculation can be simplified. It means that your teacher is teaching this all day ~