Update hidden_members.md

Author: DeveloperTryingToCodeLikeOtherOfThem

docs/hidden_members.md

@@ -17,5 +17,5 @@ Here is a list of properties and methods that can be accessed, but have an under
 11. sprite._width: Fx8
 12. sprite._height: Fx8
 
-For more information about Fixed Point Math with 8 fractional bits after the decimal point (Fx8), please read this file.
+For more information on Fixed Point Math with 8 fractional bits after the decimal point (Fx8), please read this file.
 [fixed point](https://makecode.microbit.org/---docs?md=%23%23%20Fixed%20Point%20in%20MakeCode%20Arcade%20%0A%0AFixed%20point%20is%20a%20numeric%20format%20that%20specifies%20how%20many%20fractional%20bits%20after%20the%20binary%20point.%20Microsoft%20MakeCode%20Arcade%20uses%208%20bits%20after%20the%20decimal%20point%20because%20the%20engine%20needs%20sub-pixel%20movement%2C%20performance%2C%20and%20memory.%0A)