55 × 66 + 66 × 77 + 77 × 88 + 88 × 99 the simple algorithm is: = = 55 × 66 + 66 × 77 + 77 × 88 + 88 × 99=

55 × 66 + 66 × 77 + 77 × 88 + 88 × 99 the simple algorithm is: = = 55 × 66 + 66 × 77 + 77 × 88 + 88 × 99=

=11*11*(5*6)+11*11*(6*7).+11*11*(8*9)
=121*(30+42+56+72)
=121*200
=24200

I want a hundred simple fourth grade problems

The law of exchange of multiplication: the law of exchange of addition: the law of combination of multiplication: the law of combination of addition: the law of distribution of multiplication: 2. 9.2 × 40 + 0.8 × 40 0.45 × 49 + 0.45 25 × 4.40.125 × 44 0.25 × 8.8 125 × 8.8 8 8.1 + 99 × 8.16.7 × 24-6.7