Tính nhanh a) 32.47+32.53+37.7+80.3+47.3 b) 113.38+113.62+87.62+87.38 c)123.456.321-256.444 d)43.37+93.43+57.61+69.57

Giải thích các bước giải:

a) $32.47+32.53+37.7+80.3+47.3$
$=(32.47+32.53)+37.7+80.3+37.3+10.3$
$=32.100+37(7+3)+.3(80+10)$
$=3200+37.10+3.90$
$=3200+370+270=3840$
b)$ 113.38+113.62+87.62+87.38$
$=113(38+62)+87(62+38)$
$=113.100+87.100$
$=(113+87).100=200.100=20000$
c)$123.456+456.321-256.444 =456.(123+321)-256.444$
$=456.444-256.444$
$=444(456-256)=444.200=88800$

d)$43.37+93.43+57.61+69.57=43(37+93)+57(61+69)$
$=43.130+57.130=130(43+57)=130.100=13000$