三年级奥数训练题1、用，代表三个数，有： + + = 15 ， + + =21 ， + + = 12 ， + + = （ ） x = （ ） x = （ ） x = （ ）2、 + + + + = 24 + = + + = ( ) = ( )3、 + + = 9 + + + + = 23- = 2=( ) =( ) =( )4、用，代表三个数，有： + + =9， + + =18， + + = 27 ， + + =（ ）6、 + + + = 20 (4) + + + + = 32 + = 3 + + + + + = 36 + = 9 + + + = 17=( ) =( ) =( ) =( ) =( ) =( )8、 + = 10 + + = 12 + = 6 = ( ) = ( ) = ( )9、 + + + + = 24 + = + + = ( ) = ( )10、 + = 9 + + + + = 23+ - = 2=( ) =( ) =( )11、+=200+=240=( ) =( )13、 + =80+ +=100=( ) =( )14、 + + + = 20 + = 3 + = 10 =( ) =( ) =( ) 15、 + = 10 + + = 12 + = 6 = ( ) = ( ) = ( )
