We use the formula for a sum to infinty:

S=a/(1-r) where r is the constant multiple, 0.5 and a is the starting height 8

Therefore S=8/(1-0.5)=16m total travelled

This is the same as adding 8+8/2+8/4+8/8+8/16+8/32...8/2^n

which is 8+4+2+1+0.5+0.25+0.125...which eventually reaches very close to our answer of 16.