Register Now

Login

Lost Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

222-9+11+12:2*14+14 = ? ( )

Toán Lớp 4: Tính bằng cách thuận tiện 30+31+32+……+38+39 =(30+…..)+(31+….)+……. +….+…..+….. =….

Toán Lớp 4: Tính bằng cách thuận tiện
30+31+32+……+38+39
=(30+…..)+(31+….)+…….
+….+…..+…..
=….

Comments ( 2 )

  1. 30 + 31 + 32 + … + 39
    = (30 + 35) + (31 + 39) + (32 + 38) + (33 + 37) + (34 + 36)
    = 65 + 70 + 70 + 70 + 70
    = 65 + 70 xx 4
    = 65 + 280
    = 345

  2. 30+31+32+……+38+39
    =( 30+ 35 ) + ( 31+ 39 )+……. ( 33 + 37 ) + ( 34 + 36 ) 
    = 65 + 70 + …. + 70 + 70
    = 65 + 70 x 4
    = 65 + 280
    = 345

Leave a reply

222-9+11+12:2*14+14 = ? ( )