OK, let's crack this. We're given 352 and our task is to multiply it by 20. Essentially, we'll be adding 352 to itself 20 times.
Step 1: 0 + 352 = 352
Step 2: 352 + 352 = 704
Step 3: 704 + 352 = 1056
Step 4: 1056 + 352 = 1408
Step 5: 1408 + 352 = 1760
Step 6: 1760 + 352 = 2112
Step 7: 2112 + 352 = 2464
Step 8: 2464 + 352 = 2816
Step 9: 2816 + 352 = 3168
Step 10: 3168 + 352 = 3520
Step 11: 3520 + 352 = 3872
Step 12: 3872 + 352 = 4224
Step 13: 4224 + 352 = 4576
Step 14: 4576 + 352 = 4928
Step 15: 4928 + 352 = 5280
Step 16: 5280 + 352 = 5632
Step 17: 5632 + 352 = 5984
Step 18: 5984 + 352 = 6336
Step 19: 6336 + 352 = 6688
Step 20: 6688 + 352 = 7040

So, 352*20 = 7040