OK, let's work through this together. We're starting with 315 and we're going to multiply it by 7, which means we add 315 to itself 7 times.
Step 1: 0 + 315 = 315
Step 2: 315 + 315 = 630
Step 3: 630 + 315 = 945
Step 4: 945 + 315 = 1260
Step 5: 1260 + 315 = 1575
Step 6: 1575 + 315 = 1890
Step 7: 1890 + 315 = 2205

So, 315*7 = 2205