n + n/2 + n/4 + n/8 + n/16 = 19,375

[math_celebrity]

n + n/2 + n/4 + n/8 + n/16 = 19,375

Convert to like fractions with a denominator of 16:
16n/16 + 8n/16 + 4n/16 + +2n/16 + n/16 = 19,375
31n/16 = 19,375

Cross multiply:
31n = 19,375 * 16
31n = 310000

Divide each side by 1:
31n/31 = 310000/31
n = 10,000