OK, let's work through this together. We're starting with 128 and we're going to multiply it by 7, which means we add 128 to itself 7 times.
Step 1: 0 + 128 = 128
Step 2: 128 + 128 = 256
Step 3: 256 + 128 = 384
Step 4: 384 + 128 = 512
Step 5: 512 + 128 = 640
Step 6: 640 + 128 = 768
Step 7: 768 + 128 = 896

So, 128*7 = 896