26 + 17 + 23 + 14
= ( 26 +14 ) + ( 17 +23 )
= 40 + 40
= 80
46 + 2 + 18 + 54
= ( 46 + 54 ) + ( 18 + 2 )
= 100 + 20
=120
26 + 17 + 23 + 14
= ( 26 +14 ) + ( 17 +23 )
= 40 + 40
= 80
46 + 2 + 18 + 54
= ( 46 + 54 ) + ( 18 + 2 )
= 100 + 20
=120
Bài 1: Tính nhanh:
a, 26+ 17+23+14 b, 46+ 82+ 18 + 54 c, 37- 5 + 37 -7
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50.
Tính biểu thức sau bằng cách thuận tiện nhất :
19 + 18 + 17 + 16 + 14 + 21 + 22 + 23 + 24 + 26
a 85hm5m = m
b 3km65m = m
c 2kg = g
d 23 x 7 + 46 x 7 + 129 x &
e 21 + 22 + 23 + 14 + 5 + 26 +17 + 18 +19
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27=.................................
90+67+54+23+87+98+14+78+46+28=?
1+2+3+4+5+6+7+7+8+9+10+11+12+13+14+45+15+16+17+18+19+20+21-56+56+48+52+78+84+54+2545+455+1454+1256-23+56+586=
tính nhanh: 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29=?
(nhớ la phải trình bày ra đó)