How we can find decimal between 2.15 and 2.17 ?

Find a number between 2.15 and 2.17 so one of the answers could be 2.16

2.16-2.15=0.02

The difference is 0.02
To get the number between you divide the difference by 2 then add it to the lower number.
0.02/2=0.01

2.15+0.01=2.16

The number between 2.15 and 2.17 is 2.16