How do you use the distributive property to find 9 x 99?

1 Answer
Oct 18, 2017

Answer:

#9xx99=color(red)(891)#

Explanation:

#9xx99#
#color(white)("XXX")=9xx(90+9)#

#color(white)("XXX")=underbrace(9xx90) + underbrace(9xx9)color(white)("xxx")#...the distributive property

#color(white)("XXX")=810 +81#

#color(white)("XXX")=810#
#color(white)("XX=X")ul(+color(white)(".")81)#
#color(white)("XXXXX")891#

~~~~~~~~~~~~~~ OR ~~~~~~~~~~~~~~~~~~~~~~~~~

#9xx99#
#color(white)("XXX")=9xx(100-1)#

#color(white)("XXX")=underbrace(9xx100)-underbrace(9xx1)color(white)("xxx")#...the distributive property

#color(white)("XXX")=900 -9#

#color(white)("XXX")=891#

~~~~~~~~~~~~~ OR ~~~~~~~~~~~~~~~~~~~~~~~~~~

#9xx99#
#color(white)("XXX")=(10-1)xx99#

#color(white)("XXX")=underbrace(10xx99)-underbrace(1xx99)color(white)("xxx")#...distributive property

#color(white)("XXX")=990-99#

#color(white)("XXX")=891#