Question

Tính bằng cách thuận tiện nhất : 
a ) 81 + 35 + 19 
b ) 78 + 65 + 135 + 22
c ) 234 + 17716 + 23 
d ) 85 + 99 + 1 

Answer 1

a) \(\left(81+19\right)+35=135\)

b) \(\left(78+22\right)+\left(65+135\right)=100+200=300\)

c) \(\left(234+17716\right)+23=17950+23=17973\)

d) \(\left(99+1\right)+85=100+85=185\)

Answer 2

\(a,81+35+19=\left(81+19\right)+35=100+35=135\\ b,78+65+135+22=\left(78+22\right)+\left(65+135\right)=100+200=300\\ c,234+17716+23=\left(234+17716\right)+23=17950+23=17973\\ d,85+99+1=85+\left(99+1\right)=85+100=185\)

Answer 3

A) 81+ 19 +35

=100+35=135

B) 78+65+135+22

=78+22+65+135

100+200=300 

mấy câu cx làm tương tự

Answer 4

c) 234+17716+23

=(234+16)+17700+23

=250+17700+23

=17950+23

=17973

d) 85+99+1

=85+(99+1)

=85+100

=185

 

Answer 5

a) $\left(81+19\right)+35=135$

b) $\left(78+22\right)+\left(65+135\right)=100+200=300$

c) $\left(234+17716\right)+23=17950+23=17973$

d) $\left(99+1\right)+85=100+85=185$