Multiplication Strategies for Nines

Multiple sof Nines
Look for patterns
For every multiple of 9, the digit in the tens column increases by one ten, while the digit in the ones place decreases by one.
9x2=18
9x3=27
9x4=36
9x5=45
9x6=54
9x7=63
9x8=72
9x9=81

No matter what you are multiplying by 9, as long as it is between 1 and 9, the two digits of your answer will always add up to 9.

Last pattern:
All the possible answers have reverse answers.
1x9=09   9x10=90
2x9=18   9x9=81
3x9=27    9x8=72
4x9=36    9x7=63
5x9=45    9x6=54

Also the students have learned a  hand  trick to help them with multiples of nines.