Alright, let's solve this math problem step by step. First, we have the number 357. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 60. So, we're going to take the number 357 and add it to itself 60 times.
Step 1: 0 + 357 = 357
Step 2: 357 + 357 = 714
Step 3: 714 + 357 = 1071
Step 4: 1071 + 357 = 1428
Step 5: 1428 + 357 = 1785
Step 6: 1785 + 357 = 2142
Step 7: 2142 + 357 = 2499
Step 8: 2499 + 357 = 2856
Step 9: 2856 + 357 = 3213
Step 10: 3213 + 357 = 3570
Step 11: 3570 + 357 = 3927
Step 12: 3927 + 357 = 4284
Step 13: 4284 + 357 = 4641
Step 14: 4641 + 357 = 4998
Step 15: 4998 + 357 = 5355
Step 16: 5355 + 357 = 5712
Step 17: 5712 + 357 = 6069
Step 18: 6069 + 357 = 6426
Step 19: 6426 + 357 = 6783
Step 20: 6783 + 357 = 7140
Step 21: 7140 + 357 = 7497
Step 22: 7497 + 357 = 7854
Step 23: 7854 + 357 = 8211
Step 24: 8211 + 357 = 8568
Step 25: 8568 + 357 = 8925
Step 26: 8925 + 357 = 9282
Step 27: 9282 + 357 = 9639
Step 28: 9639 + 357 = 9996
Step 29: 9996 + 357 = 10353
Step 30: 10353 + 357 = 10710
Step 31: 10710 + 357 = 11067
Step 32: 11067 + 357 = 11424
Step 33: 11424 + 357 = 11781
Step 34: 11781 + 357 = 12138
Step 35: 12138 + 357 = 12495
Step 36: 12495 + 357 = 12852
Step 37: 12852 + 357 = 13209
Step 38: 13209 + 357 = 13566
Step 39: 13566 + 357 = 13923
Step 40: 13923 + 357 = 14280
Step 41: 14280 + 357 = 14637
Step 42: 14637 + 357 = 14994
Step 43: 14994 + 357 = 15351
Step 44: 15351 + 357 = 15708
Step 45: 15708 + 357 = 16065
Step 46: 16065 + 357 = 16422
Step 47: 16422 + 357 = 16779
Step 48: 16779 + 357 = 17136
Step 49: 17136 + 357 = 17493
Step 50: 17493 + 357 = 17850
Step 51: 17850 + 357 = 18207
Step 52: 18207 + 357 = 18564
Step 53: 18564 + 357 = 18921
Step 54: 18921 + 357 = 19278
Step 55: 19278 + 357 = 19635
Step 56: 19635 + 357 = 19992
Step 57: 19992 + 357 = 20349
Step 58: 20349 + 357 = 20706
Step 59: 20706 + 357 = 21063
Step 60: 21063 + 357 = 21420

So, 357*60 = 21420