Question

Suppose you were given Php 1,000,000,000. How long would it take to have less than five pesos left if you spent half of it every day?

Answer 1

Assuming that he is spending half of what is left everyday

After first day reminder is $=\frac{1}{2}×10^9$

$n^{th}$ day the reminder will be $=(\frac{1}{2})^{n}×10^9<5$

$\frac{10^{9}}{5}<(\frac{1}{2})^{-n}$

Taking logs both sides

log$(2×10^{8})<-n\>log\>0.5$

$8.3010<0.3010n$

$27.58<n$

$\therefore$ Number of days $=28 days$