Question

用简便方法计算下面各题.

(1)7.86+9.73+2.14+0.27 (2)216.45-(4.5+1.45) (3)(1/13X1/18)X13X18(4)999X778X333X666 (6)9又1/3+99又1/3+999又1/3+2

Answer 1

(1)7.86+9.73+2.14+0.27
=（7.86+2.14）+（9.73+0.27）
=10+10
=20
(2)216.45-(4.5+1.45)
=216.45-1.45-4.5
=215-4.5
=210.5
(3)(1/13X1/18)X13X18
=18*13
=（20-2）*13
=260-26
=234
(4)999X778+333X666
=999*（778+222）
=999000
(6)9又1/3+99又1/3+999又1/3+2

=（9+99+999）+（1/3 *3)+2
=1110-3+3
=1110 .

Answer 2

1)7.86+9.73+2.14+0.27
=(7.86+2.14)+(9.73+0.27)
=10+10
=20
2)216.45-(4.5+1.45)
=216.45-1.45-4.5
=215-4.5
=210.5
(3)(1/13X1/18)X13X18
=(1/13X13)X(1/18X18)
=1x1
=1
(4)999X778X333X666
有问题吧
(6)9又1/3+99又1/3+999又1/3+2
=10-2/3+100-2/3+1000-2/3+2
=(10+100+1000)-3x2/3+2
=1110-2+2
=1110

Answer 3

(1)7.86+9.73+2.14+0.27
=7.86+2.14+9.73+0.27
=10+10=20

(2)216.45-(4.5+1.45)
=216.45-1.45-4.5=210

(3)(1/13X1/18)X13X18
=1/13*13*1/18*18=1*1=1

(4)999X778X333X666
=

(6)9又1/3+99又1/3+999又1/3+2
=9+1/3+99+1/3+999+1/3+2
=1110