A guardian gave a child some money. The child used 2/5 of the money to buy sugar and 5/9 of the remaining money to buy rice. If the child deposited the rest of the money, which was UGX 40,000, find th

Money used for sugar $= \frac{2}{5}M$.

Remaining money $= M - \frac{2}{5}M = \frac{3}{5}M$.

Money for rice $= \frac{5}{9}$ of the remaining money.
Money for rice $= \frac{5}{9} \times \frac{3}{5}M = \frac{15}{45}M = \frac{1}{3}M$.

Total fraction spent $= \frac{2}{5}M + \frac{1}{3}M = \frac{6}{15}M + \frac{5}{15}M = \frac{11}{15}M$.

The money deposited is the balance.
Fraction deposited $= M - \frac{11}{15}M = \frac{4}{15}M$.

We know that $\frac{4}{15}M = \text{UGX } 40,000$.

The total money given was UGX 150,000.

Money for sugar $= \frac{2}{5} \times 150,000 = \text{UGX } 60,000$.
Money for rice $= \frac{1}{3} \times 150,000 = \text{UGX } 50,000$.
Money deposited $= \text{UGX } 40,000$.
Total spent and deposited $= 60,000 + 50,000 + 40,000 = \text{UGX } 150,000$.

Divide 78 by 4 and record the remainders.

The PIN is $1032_4$.
The correct PIN is $\boxed{1032}$.