math
posted by mj .
If you run 1 mile on Monday and then double everyday how many miles will you run by friday?

16 mile on Friday
I hope this is your answer 
by Friday you have run
1+2+4+8+16 = 31 miles
that's by the end of Friday. By the time yo got up on Friday, you have only run 15 miles. Be precise in your language if you want a precise answer. "by Friday" is unclear. 
monday=1 mile
tuesday=2*1=2miles
wed=2*2=4 miles
thursday=4*2=8miles
friday=8*2=16miles
total miles=1+2+4+8+16
=31 miles
hope u might understood it!!!