Sure thing, let's get straight to it. We start with 420 and we're going to multiply it by 11, which means adding 420 to itself 11 times.
Step 1: 0 + 420 = 420
Step 2: 420 + 420 = 840
Step 3: 840 + 420 = 1260
Step 4: 1260 + 420 = 1680
Step 5: 1680 + 420 = 2100
Step 6: 2100 + 420 = 2520
Step 7: 2520 + 420 = 2940
Step 8: 2940 + 420 = 3360
Step 9: 3360 + 420 = 3780
Step 10: 3780 + 420 = 4200
Step 11: 4200 + 420 = 4620

So, 420*11 = 4620