10
N + 9
If a number is added to itself, it is twice that number → 18 ÷ 2 = 9 → 9 + 9 = 18
9/10 divided by 10/9 equals 9/10 x 9/10 equals 81 /100
The straight line is added to the second 1 which changed it to a "t", making it 10 to 10 (9:50).
.9
NO.
-9
3
(9 × 10) + 712 = 802
-19
First 9 X 10 is easy to calculate. Any number times 10 is that number with a 0 added.9 X 10 = 90Then you just add the 9 to it to have the same answer as if you multiplied 9 X 11.90 + 9 = 99or9 X 11 = 99
109
9 and 1
it means "great" because of gr8 but people added 9 and 10 for humor
18
It is the same as: -9 +10 = 1