Without delay, let's solve this. We've got 256 and we will be multiplying it by 15, that is, adding 256 to itself 15 times.
Step 1: 0 + 256 = 256
Step 2: 256 + 256 = 512
Step 3: 512 + 256 = 768
Step 4: 768 + 256 = 1024
Step 5: 1024 + 256 = 1280
Step 6: 1280 + 256 = 1536
Step 7: 1536 + 256 = 1792
Step 8: 1792 + 256 = 2048
Step 9: 2048 + 256 = 2304
Step 10: 2304 + 256 = 2560
Step 11: 2560 + 256 = 2816
Step 12: 2816 + 256 = 3072
Step 13: 3072 + 256 = 3328
Step 14: 3328 + 256 = 3584
Step 15: 3584 + 256 = 3840

So, 256*15 = 3840