Hexadecimal Equations (Problem $4$ , Version $2$ )

$2 \times 6 \times 18 = 216$

$3 \times 9 \times 27 = 729$

$3 \times 16 = 48$

$2 \times 256 \times 10 \times 5 = 25600$

$216F + 729B + 3D + 48C + 2A + 25600E$

$F = 15, B = 11, D = 13, C = 12, A = 10, E = 14$

$2 \times 16^3 + 1 \times 16^2 + 6 \times 16^1 = 2 \times 4096 + 1 \times 256 + 6 \times 16 = 8192 + 256 + 96 = 8544 + 15 = 8559$

$7 \times 16^3 + 2 \times 16^2 + 9 \times 16^1 = 7 \times 4096 + 2 \times 256 + 9 \times 16 = 28672 + 512 + 144 = 29328 + 11 = 29339$

$3 \times 16^1 = 3 \times 16 = 48 + 13 = 61$

$4 \times 16^2 + 8 \times 16^1 = 4 \times 256 + 8 \times 16 = 1024 + 128 = 1152 + 12 = 1164$

$2 \times 16^1 = 2 \times 16 = 32 + 10 = 42$

$2 \times 16^5 + 5 \times 16^4 + 6 \times 16^3 + 0 \times 16^2 + 0 \times 16^1 = 2 \times 1048576 + 5 \times 65536 + 6 \times 4096 = 2097152 + 327680 + 24576 = 2449408 + 14 = 2449422$

$8559 + 29339 + 61 + 1164 + 42 + 2449422$

$8559 + 29339 + 1206 + 61 + 2449422$

$8559 + 29339 + 1267 + 2449422$

$8559 + 29339 + 1267 + 2449422$

$37898 + 1267 + 2449422$

$2487320 + 1267$

$2488587$

Answer $\rightarrow \fbox{2488587}$

For the Bonus:

$2488587$

Do division by $16$ to obtain the L.H.S of the modulo calculations.

$2488587 (\text{mod}(16)) = 11$

$155536 (\text{mod}(16)) = 0$

$9721 (\text{mod}(16)) = 9$

$607 (\text{mod}(16)) = 15$

$37 (\text{mod}(16)) = 5$

$2 (\text{mod}(16)) = 2$

Read the remainders from bottom to top:

$25159011$

Since $F = 15, B = 11$ :

$25F90B$

Bonus Answer $\rightarrow 25F90B$