3333×5555+6×4444×2222

=3333×5555+(4×3/2)×4444×2222

=3333×5555+3/2×2222×4444×4

=3333×5555+3333×4444×( 1+3)

=3333×5555+3333×4444+3333×4444×3

=3333×(5555+4444)+4444×9999

=3333×9999+4444×9999

=9999×(3333+4444)

=( 10000- 1)×7777

=77770000-7777

=77762223

Note: Tell children that there are generally three clever methods for this clever calculation, namely, splitting and rounding, and rounding up to 9 (rounding up to 9 includes 9, 99, 999, etc.). ), and then round it off, that is, it becomes 10- 1, 100- 1.

This problem applies to integer, 9 and integer.