How much does it equal to 1 / 1999 + 2 / 1999, which has been added to 1998 / 1999?

How much does it equal to 1 / 1999 + 2 / 1999, which has been added to 1998 / 1999?

1 / 1999 + 2 / 1999. Up to 1998 / 1999
=(1/1999+1998/1999)×1998÷2
=1998÷2
=999

What is 1 + 2 + 3. + 1998 + 1999 + 1998 +. + 3 + 2 + 1

The number is 3998001

What is 1.2 * 99 + 1.2 * 98?

1.2*99+1.2*98
=1.2*(99+98)
=1.2*197
=236.4

Known (2000-a) (1998-a) = 1999, ask (2000-a) &# 178; + (1998-a) &# 178; =? That person with a high degree must help me

（2000-A）²+（1998-A）²=（2000-A）²+（1998-A）²-2（2000-A) (1998-A)+2（2000-A) (1998-A)=[(2000-A)-(1998-A)] ²+ 2（2000-A) (1998-A)=4+2*1999=4+2*(2000-1)=4000-2+4=4002...