Tính nhanh :
\(\left(1999+313\right)-1999\)
\(=\left(1999-1999\right)+313\)
\(=0+313\)
=\(=313\)
\(a,\left(1999+313\right)-1999\)
\(=2312-1999\)
\(=313\)
(1999 + 313) - 1999
=(1999-1999) +313
=0+313
=313
!!!
a) (1999+313)-1999
=1999+313-1999
=(1999-1999)+313
=0+313
=313
(1999+313)-1999 =1999+313 -1999=1999-1999+313 = 0+313=313