OK, let's work through this together. We're starting with 358 and we're going to multiply it by 15, which means we add 358 to itself 15 times.
Step 1: 0 + 358 = 358
Step 2: 358 + 358 = 716
Step 3: 716 + 358 = 1074
Step 4: 1074 + 358 = 1432
Step 5: 1432 + 358 = 1790
Step 6: 1790 + 358 = 2148
Step 7: 2148 + 358 = 2506
Step 8: 2506 + 358 = 2864
Step 9: 2864 + 358 = 3222
Step 10: 3222 + 358 = 3580
Step 11: 3580 + 358 = 3938
Step 12: 3938 + 358 = 4296
Step 13: 4296 + 358 = 4654
Step 14: 4654 + 358 = 5012
Step 15: 5012 + 358 = 5370

So, 358*15 = 5370