Siete preguntas de cálculo sencillas
1. 42×29-18×42-21×2
=42×29-18×42-42
=42×(29-18-1)
=42×10
=420
2, 172×56-79×36-93×36
=172×56-( 79 93)×36
=172×56-172×36
=172×(56-360
=172×20
=3440
3, 349×13 349×39 349×48
=349×(13 39 48)
=349×100 p>p>
=34900
4 (425×5776-425 4225×425)÷125÷8
=425×(5776-1-4225)÷ (125 ×8)
=425×1550÷1000
=658,75
5, 99999×99999 199999
=99999× (100000 -1) 100000 99999
=9999900000-99999 100000 99999
=(9999900000 100000) (99999-99999)
=10000000000 0
=10000000000
6, 2004×20052005-2005×20042004
=2004×2005×10001-2005×2004×10001
=2004 ×2005 ×(10001-10001)
=2004×2005×0
=0
7, 20042005×20052004-20042004×20052005
== (20042004 1)×(20052005-1)-20042004*20052005
= 20042004×20052005-20042004 20052005-1-20042004×20052005
=(200420 0 4 ×20052005- 20042004×20052005)-2004×10001 2005×10001-1
=0 10001×(2005-2004)-1
= 10001-1
= 10000