20
10 is the number halfway between -5 and 15.It is: 5
15
Exactly halfway between them is 10.15.
0.19 is halfway between those two numbers.
20
halfway between 154 and 164 is 10
10 is the number halfway between -5 and 15.It is: 5
Halfway between 10 and 15 is (10 + 15) ÷ 2 = 121/2
10
15
-5
Exactly halfway between them is 10.15.
There is no "the" rational" number since there is an infinity of them. Start with the number halfway between the two: (1/10+1/11)/2 = 21/220. Then try halfway between 1/10 and 21/220, and then halfway between 1/10 and that on. And so on.
No, 105 is not a square number. It is between 10^2 (100) and 11^2 (121).
30
It is 10, the number halfway between them.