Sure thing, let's get straight to it. We start with 48 and we're going to multiply it by 21, which means adding 48 to itself 21 times.
Step 1: 0 + 48 = 48
Step 2: 48 + 48 = 96
Step 3: 96 + 48 = 144
Step 4: 144 + 48 = 192
Step 5: 192 + 48 = 240
Step 6: 240 + 48 = 288
Step 7: 288 + 48 = 336
Step 8: 336 + 48 = 384
Step 9: 384 + 48 = 432
Step 10: 432 + 48 = 480
Step 11: 480 + 48 = 528
Step 12: 528 + 48 = 576
Step 13: 576 + 48 = 624
Step 14: 624 + 48 = 672
Step 15: 672 + 48 = 720
Step 16: 720 + 48 = 768
Step 17: 768 + 48 = 816
Step 18: 816 + 48 = 864
Step 19: 864 + 48 = 912
Step 20: 912 + 48 = 960
Step 21: 960 + 48 = 1008

So, 48*21 = 1008