The answer is 9.
How I remember the 9 times tables is this.
1×9=9
2×9=18 (18, think 1+8=9)
3×9=27 (27, think 2+7=9)
4×9=36 (36, think 3+6=9)
5×9=45 (45, think 4+5=9)
and so on
So for 6×9, subtract 1 from 6, which gives you the first digit 5.
Then, think 5 + what gives me 9?
5+4, right?
So your answer is 54.
