Simple calculation: 1) 2000 by 2001, 2) 3 by 8, 0.25 plus 1 by 4, 5 by 8, minus 1 by 4 ③ 17 out of 20 times 2 out of 3 plus 17 out of 20 times 1 out of 3 minus 1 out of 2

Simple calculation: 1) 2000 by 2001, 2) 3 by 8, 0.25 plus 1 by 4, 5 by 8, minus 1 by 4 ③ 17 out of 20 times 2 out of 3 plus 17 out of 20 times 1 out of 3 minus 1 out of 2

2000 X ( 2000 /2001 )
= 2000 X ( 1 - 1/2001 )
= 2000 - 2000/2001
= 1999 + 1/2001
3/8 X 0.25 + 1/4 X 5/8 - 1/4
= 1/4 X 3/8 + 1/4 X 5/8 - 1/4
= 1/4 X ( 3/8 + 5/8 - 1 )
= 1/4 X ( 8/8 - 1 )
= 0
17/20 X 2/3 + 17/20 X 1/3 - 1/2
= 17/20 X ( 2/3 + 1/3 ) - 1/2
= 17/20 X 3/3 - 1/2
= 17/20 - 10/20
= 7/20
( 2008+ 1/2007 ) X ( 2007 /2008 )
= 2008 X 2007/2008 + 2007/2008 X 1/2007
= 2007 + 1/2008