OK, let's work through this together. We're starting with 210 and we're going to multiply it by 7, which means we add 210 to itself 7 times.
Step 1: 0 + 210 = 210
Step 2: 210 + 210 = 420
Step 3: 420 + 210 = 630
Step 4: 630 + 210 = 840
Step 5: 840 + 210 = 1050
Step 6: 1050 + 210 = 1260
Step 7: 1260 + 210 = 1470

So, 210*7 = 1470