Sure thing, let's get straight to it. We start with 236 and we're going to multiply it by 21, which means adding 236 to itself 21 times.
Step 1: 0 + 236 = 236
Step 2: 236 + 236 = 472
Step 3: 472 + 236 = 708
Step 4: 708 + 236 = 944
Step 5: 944 + 236 = 1180
Step 6: 1180 + 236 = 1416
Step 7: 1416 + 236 = 1652
Step 8: 1652 + 236 = 1888
Step 9: 1888 + 236 = 2124
Step 10: 2124 + 236 = 2360
Step 11: 2360 + 236 = 2596
Step 12: 2596 + 236 = 2832
Step 13: 2832 + 236 = 3068
Step 14: 3068 + 236 = 3304
Step 15: 3304 + 236 = 3540
Step 16: 3540 + 236 = 3776
Step 17: 3776 + 236 = 4012
Step 18: 4012 + 236 = 4248
Step 19: 4248 + 236 = 4484
Step 20: 4484 + 236 = 4720
Step 21: 4720 + 236 = 4956

So, 236*21 = 4956